This is going to be tough - you have to be cruel to be kind. Don't let your guilt over not being an involved dad during his teenage years get in the way. Doing everything for him now won't make up for that anyway and you are not doing him any favours trying to sort his life out for him. Of course you must help him (as you are doing), but it sounds like he will simply let you!
He is no longer a child, but if he is unable to discipline himself (because he has nothing he has to do), you must set clear rules and tasks so you share the responsibilities of running the house, cooking, shopping etc. Easier said than done, but persist. You might find that showing you expect and trust him to do his designated chores means he lives up to that expectation (rather than just ordering him to do stuff). I have always expected my kids (both teenagers now, one boy, one girl) to do some household chores. I work full-time and am now a single parent, so if we are going to live in a civilised household, without me feeling like a complete drudge and a slave, then they have to pitch in. Obviously, I do most of it, but things like helping with the laundry, sweeping stairs, vacuuming, unloading/loading dishwasher and doing some simple cooking (and clearing up afterwards!) isn't beyond them.
You could try sitting him down, adult to adult, and explaining all that has to be done and asking him how it would be best to divide it between you - for example, he might enjoy cooking but hate clearing up, so you could agree he would do more cooking and you do more clearing, rather than just take it in turns. But that might be a tad optimistic!
He might be able to get a retail job in a supermarket or DIY type store: with Sunday trading and 24/7 shopping, there are more opportunities and he'd be earning a wage. Appreciate that location/transport could be an issue. If he can't get a job, then you have to explain that volunteering is a way in - as you meet people, get the chance to network and gain experience (as you clearly know!). Suggest he looks on it as an investment for the future rather than 'working for no pay'.
I think you have to try to set a daily routine for him - expectations again - so he doesn't just lounge in bed. If he doesn't comply, he doesn't eat (easy to say, very hard to do!). I wonder if you might try emailing him a letter voicing your concerns, rather than trying to have these difficult conversations with him, that can lead to either silence or rows. Easier for him - and easier for you, too. I have found this useful with my teenage son. We also text a lot.
Sorry for this long screed, but I really feel for you in this predicament. I do think what the Americans call 'tough love' is called for here - or you could both go mad!