All of this.
Did he move in ahead of lockdown so that you could bubble & maintain the relationship OP?
Time to take a long, cool look at what he actually brings to your life.
Does he pay his way? Share half all costs, do half the chores, half the shopping & cooking, half the mental load?
Or is he what I suspect he is - a manchild who's landed on his feet in your home?
Before you started dating him - did you sleep a lot better?
Because I suspect a lot of this is the constant daily/nightly stress of knowing you are going to get woken, the anger of knowing he won't listen to you or make changes, & a lot of unacknowledged sadness that this is maybe not the man for you after all. That would be bound to fuck up the sleep of someone who's already managing shift/sleep patterns.
And I'm with the PP upthread who noted that you had a big talk about this before he even moved in - he pretended to 'understand' but changed nothing.
So instead of him making a simple change to where he sleeps, you started self-medding with zopiclone.
After he moved in, he still refused to change his ways, & you ended up self-medding with alcohol.
What will you use to self-medicate when he STILL refuses to sleep elsewhere on his late gaming nights? Valium? Opiates?
Because something tells me this man will 'forget' or tell you 'not to make a fuss', or find someone to blame. If it's not the dog, it's going to be you - he'll be telling you you're unreasonable & "too sensitive" next.
Now you have asked him to come up with a plan (like he hasn't know of YOUR simple plan, for 3 fucking years already). You seem to believe that he will do so this time -
I sent him a frank message before I started work and got an apology without an excuse.
What will happen if you find out that - yet again - he will mouth some words but not change his actions?
You seem relieved that he didn't make an excuse. (You had expected one - eg he'd blame the dog) Like that is a huge step forward. Can you see how low a bar that is to have? It's the least any partner should expect from another!