I would look into sensory seeking profile as well (maybe The Out of Sync Child?) and for sure the Stuart Shanker / Self-Reg stuff. I didn't find the Self-Reg book very useful on its own, I only found it useful from combining with finding every podcast I could where he is interviewed and all the talks of his on youtube and putting it all together, plus other resources which explain about the autonomic nervous system and how the sympathetic and parasympathetic nervous system work together to regulate arousal level based on the currently perceived level of threat.
Sugar is an interesting one because so many people report seeing changes with sugar whereas in double-blind trials, there are no reported differences in behaviour, however there is a strong difference in behaviour when parents think their child has had sugar. I think more research may be needed here, but I do think that some people are more sensitive to blood sugar levels and it can affect regulation, or it may be you are seeing some kind of secondary effect, like sugar causing a release of dopamine and you're actually seeing the effect of dopamine? Be careful with this, because there is a lot of junk science which is popular now particularly regarding dopamine, but I would look at the role of dopamine specifically in relation to ADHD / executive functioning skills, addictive behaviours, and the nervous system.
On the topics of podcasts, there were a couple on SENDCast with Clare Truman about PDA which were brilliant.
I actually do think that giving kids a sense of responsibility for a communal goal, which could mean chores, is extremely helpful and valuable in helping them position/orient themselves as useful and competent and needed within a family, and can help with an egalitarian approach because otherwise it is more like adults are doing things for children which is a different role. I would not force this, as that can be counterproductive, but it may be a useful conversation to have when everyone is calm. Another useful thing to do which I think is great here is talking to them about their family story/history which can help ground them in time and place and support a positive identity. Identifying strengths is also good, it sounds like you are doing this already.
You might find some of the ADHD Dude stuff helpful as well. However, he does lean strongly towards the mindset that adults need to be in charge and children need to learn/understand that structure to succeed, so I'm a bit on the fence about whether his approach will work for all families. But I do think he has some very useful things to say pointing out patterns that he sees of families who have let the balance tip too far the other way, so the child is effectively in control.
I am very far from an expert so please take my opinion for what it is here: I do think for the autonomous/collaborative thing to work, it only works if there is balance. You can either run a household where the parents are in charge, or where everyone is in charge of themselves, but the parents are a sort of safety net/balance check, what is dysfunctional is when children (or more usually, one child) is essentially controlling everything because the adults are trying to avoid meltdowns and essentially only avoid meltdowns.
If you find yourself in that situation, then it might be helpful to look at some of the approaches where you don't engage with the conflict in the moment, or use de-escalation techniques in the moment, but then what happens outside the moment is fairly crucial. For some children/a more collaborative approach, where they are distressed by their own behaviour when they are in that fight or flight state because it makes them feel out of control, and they already recognise that it's an out of proportion reaction, then it might be that you don't need to address that aggressive behaviour directly because they don't want to be aggressive and they actually would welcome tools to not get into that state in the first place, so looking at overall regulation, reducing stressors, (Self-Reg) looking at trigger situations individually and seeing their point of view (The Explosive Child) as well as helping support them with self-regulation skills (e.g. mindfulness, biofeedback, heavy work, physical exercise, breathing techniques, redirection) and any medication/therapy which may be useful, this can all help reduce the amount of meltdowns in the first place and over time the child gets better at recognising their own sort of "meltdown likelihood status" and managing it (literally, self-regulating) and also advocating for their own needs, opting for outside-the-box solutions if they need to.
However, if you have the situation of a child who actually quite likes going into the fight-or-flight state on some level, because it makes them feel powerful and/or it gets them what they want, or they think (once they have calmed down) that they are totally in the right even if they can parrot off yes I know I was not supposed to do that, or if they are feeling "I know I shouldn't hit/shout but there is no other way to get what I want" then there may be a value to adding some kind of external accountability (which to be clear, means a minor/token punishment) outside of the moment, for the aggressive behaviour which happened within the moment. You STILL deescalate or disengage during the actual event itself and it is useful if you do remind them of the house rules/consequences in the moment that you do it in a disengaged way, rather than presenting it as a kind of counter threat/weapon to try and get them to back down in the moment, which is how "typical parenting" generally uses threat of consequences. But anyway, there are some good guidelines for how to do this within the ADHD Dude stuff and also in the Who's In Charge book.