Your parents have shared their concerns about DS2. They are also concerned about you & the considerable challenges you are facing.
They have given you & DS2 a safe berth while you get yourself sorted out & back on an even keel. So try not to look a parental gift-horse in the mouth. Bear in mind that it is their home, their routines & ways of doing things.
Please take a moment to consider the options available to you, by comparison are they favourable?
Toddlers can be hard work by anyone’s candle. You have loyal loving parents - whatever ‘old school’ means - who are there with you. You may find their parenting style restrictive, but your DS may thrive on it, particularly after recent disruptions. Let (or tell if need be) them take up some of the everyday childcare responsibilities, get involved in looking after DS, undertake some toddler wrangling, take him out to the park for swings & duck feeding, do bathtime, read stories, even do the tidying up & laundry for him.
Take a big deep breath, hover nearby, & let your parents prepare & feed DS a few lunches. Let them show you what they mean, rather than speak to you about it. You may find out something, so might they about your DS & his true preferences. For example, DS is old enough to sit up at table with family for lunch at home, granted it may be a bit messy & conversation limited, but is how children learn to eat well & socialise. Have them do this, it can go either way, they all have fun &/or maybe your parents see things differently, more from your pov. Who knows, but give it a go?
Ask them to help you with his everyday stuff, so that they bond with their GS & more importantly you have a break to catch your breath.