It doesn't sound great from a relationship POV, the drinking and lying about working to get pissed but putting this aside, you're worried about another human being.
I would try calling the restaurant, explain you don't want any details other than thas he been seen or heard from since Saturday, you just want to know he's safe. If they refuse to say and you're genuinely concerned, you could try knocking at his or popping into work. Again, reiterate you think he has lost his phone and you just want to know if he's safe, you're not looking to disturb him at work. Does he have housemates? If none of these turn up any answers, and you don't have contact details for his friends, I would consider handing it over to the police to look into.
Don't get me wrong, I have been ghosted, I have been out with men who pull disappearing acts, also lost my phone once or twice over the years after a night out. However, I also live alone in a big city and worry that if anything happened to me, it could be days before anyone noticed, especially if over a weekend.
Just my POV which is that the likelihood is nothing bad has happened but if this is out of character after 9-10 months, you are not being OTT for wanting to check things out. If he had blocked you or was online that would be different.
If he has just gone off grid after a bender though, with ongoing drinking issues, I wouldn't think twice about calling time on the relationship, there will just be more of this to come