From my experience, it might be better to try gaming on a stable distro rather than a gaming distro to get a better feel for Linux first. Seems you already have some experience of that already, so here are the gaming distros I've tried and some thoughts about them. Keep in mind I've been using AMD stuff for my latest computers, but I do have an Nvidia laptop that I don't game much on but often run the same distro on.

Solous was the first gaming distro I've tried, might be close to ten years ago, so memory is kinda fuzzy. But it had support for most of the things you needed for gaming out of the box back then, which was rare. Development on it kinda went into a standstill or something, which made me go distro jumping.

Manjaro was where I ended up. Most everything worked out of the box. I ran it for a long time, but there are some problems in how it's being managed. The Arch but not Arch approach made it feel unstable sometimes. So when I made a new computer, I distro jumped again.

Nobara which build on Fedora was much more stable than Manjaro had been for me. I had no real problems with it. Lots of patches and tweaks to make gaming a smoother experience build in. But I've stated eyeing the atomic OS that had been pooping up. The benefit of not having to run a custom-made updater every time you wanted to update made me do the latest jump.

Bazzite is built on an atomic Fedora, so some settings and tweaks are a bit harder to do. But the benefit is that updates are automatic, and it comes with a lot of good tools and guides on how to work with an atomic OS. As a power user, you will have to familiarize yourself with containers to get full use of it. I'm not gonna lie, the out-of-the-box experience was a bit smother on Nobara, but I don't really see me going back.

Pop!_OS I've never really given it a good chance. I did try it for shorter periods, a couple of years apart. One time I just did not like its default windows manager and another it did not have support for my GPU.

Looking through the JRPGs I own, most of them with adult cast are western made. Depending on how far you go with j-influenced some might fit on your list. Zeboyd games is a western studio making JRPG like games with their own twist on them. Cosmic Star Heroine have a completely adult cast. Been years since I played through the Cthulhu games, but I remember the cast being mostly adults in them.

CrossCode from Radical Fish Games stretches what I consider a JRPG to be, but it still comes up in my library when searching for the tag. I think most of the cast were young adults rather than children.

Fell Seal: Arbiter's Mark by 6 Eyes Studio is pretty much a Final Fantasy Tactics.

Here are two 3D platformers I haven't really heard a lot of but still had very fun with last year.

Demon Turf - 335 Reviews What pulled me in initially was the art syle, the games looks a bit like the cartoons from my childhood. This one got combat, exploration, bosses, collectables. A bit of a problem is that the game tried to do a lot of things at the same time, resulting in a bit uneven quality overall. There are also leaderboards if you into speedrunning.

Demon Turf: Neon Splash - 105 Reviews Some kind of standalone DLC/spinoff to the first game. In this game everything is more streamlined and the design feels more focused. Combat have been cut in order to give the platforming more time to shine and a reason to simplify the controls. The focus is on repeating the same levels for better a time on the leaderboard. Speedrunning is not really my thing but I still found enjoyment in the game. Much cheaper and short than Demon Turf.