Oh yeah a Sburb Roguelite has been something I thought would be really cool for the longest time too! I can imagine it actually wouldn't be too terribly hard (relatively speaking) to make a fangame of. I mean, of course, game development is HARD, but it seems more possible than just trying to make sburb itself and all of it's advanced mechanics. Focus more on just themes of things with a couple of unique sburby mechanics. I even once brainstormed some roguelite mechanics myself and thought it'd be cool if the house building part of sburb would instead be sort of like an NPC housing thing kind of like Cult of the Lamb, you'd get consorts or other people to move in and you can upgrade your base of operations and such.

That being said, I've been working out the idea for my own Sburbventure for a while now kind of inspired by Monopoly, which, despite my love for the roguelite action elements brought up here, would focus much more on building and even automation, so it becomes a city builder sim where you have to house consorts and build your society. Which I think could work well for a sburb game trying to prepare it's players in running a universe, by giving them responsibility over building their land up to being a functional society (albeit one of consorts lol). Of course it'd have elements of buying land, and possible even economics, conflict, diplomacy, etc. I think it'd be fun to explore.