I think I mostly liked those type-systems that lean towards dependent, but not go all the way.
Purescript might be favourite? Even by default you get more power than i.e. vanilla Haskell, with row-types. But then you can get type-level list, typelevel string, even typelevel regex! And you use these through type-classes in a kind of logic-programming way.
Find some thing you enjoy creating digitally and just do that and publish.
Straight ort is probably toughest to sell, but ... if you enjoy it, one day there might be enough fans to sign up to patreon, buy your prints, book, e.t.c.
Like, you are probably choosing the Brandon Sanderson route, "Even if I never publish any of these novels, and I will die with 20 books worth of written stories that almost nobody knows about, it was still worth it!" As late sit pterry said, "Writing is the most fun you can have by yourself." You probably won't become next Sanderson or next Weir (Martian was self-published as a web-series) ... I would think that if you find your audience, you could become someone like qntm?
Also, books that teach about stuff have easier time finding an audience.
Especially if you already have a hobby that you can write about. This is the thing, you need something you are excited about or at least persistent about doing. My partner has been training dogs for over a decade, and writing training plans is not as lucrative to have as the main income, but it scales better than training in person, right ;)
Simmilarily, you could make games, publish them on itch and probably won't become next Maddy Thorne (of Celleste fame) but you could become new Brozef (look up Felvidek, it started as his university ...thesis? I think? And now it is like a game on steam and people even bought it!)
Boardgames/tabletop can be a thing - itch can work there too, but there might be a local game jam where you could cobble something together and then somebody might print&play it?
People still like to get ~human made assets. 2d art. 3d models. I used to faf around in blender a decade ago and even I heeded the siren call of a well rigged character for 10$ :D
Yeah ... reading this after myself - you are thinking the wrong way around. You need something you are excited about or at least persistent about doing. If you have several, yeah thinking about which one is more commercially viable can be good. If you have something concrete in mind, that is like a project that is good too, but you should be honest with yourself if you really need the money, or if this is a "eh, could be nice if something comes out of it, but it was time well spent even if not"
Recently I have been writing more stings in jsonnet. If I were with more haskell-friendly team, might even try dhall. In general, I feel like writing the yaml in something else than yaml is the way to go, and as long as you get imports and way to do templating that is not just string interpolation, you are good.
T.b.h. if I were to write a manifest generator, I would still probably commit the thing into a repo and let argo do the rest. Maybe even fiddled around to make the generator into a config-management-plugin ... but that feels like over-doing it.
Fedora is good. Ubuntu is still good. Weirdly - if he has steam-deck and a desktop setup, fiddling around with steam-os in desktop mode can be a good enough entry-point.
I would actually look at EU countries? Maybe if you feel like your country of origin is too much of a backwater, sure, look further, but as long as you are within EU, university courses come between 1k and 5k/semester? Which, even with the more expensive option, you are well below 60k.
And - you probably are too off path for "I am going to pick school for the prestige credentials", you already have 8 years of SWE in your CV, it is fine if your uni will be something random in Europe that works under Bologna Process.
So - focus on schools that seem to be teaching well - or possibly, if you have becomming an academic in your sights, ones that would support that well. Also, I have several friends in their 30's and 40's doing university courses targeted at working people - they have weekend courses every other weekend and otherwise self study. They will end up with proper diploma and everything.
Dancing. Roughly once a month I go to some small festival nearby, mostly live music - either oldschool swing, or blues and dance my hear out. These are not too big, like between 200 and 500 people? And I am mostly recognizing the core 100 by their faces, and more and more of them are genuine friends.
Took me around a year or two of several hours a week in courses to become comfortably intermediate in my dancing skills, and from that point onwards, it is mostly just fun!
Purescript might be favourite? Even by default you get more power than i.e. vanilla Haskell, with row-types. But then you can get type-level list, typelevel string, even typelevel regex! And you use these through type-classes in a kind of logic-programming way.