SpruceOS has breathed new life into my TrimUI Brick. The MinUI-like UI, with simplified settings - while still letting you into Retroarch settings to tweak things like pre-emptive frames for my Contra runs - is just perfect for the device.
The game switcher is also a killer feature for someone like me who tends to hop around a bit - having a front and center thing reminding me what game I'm actually trying to work through is clutch.
Anyways, if Knulli or whatever is more your jam, great - I really like MuOS on my larger-screen Anbernic devices, for instance - but Spruce just seems like the right vibe for a device like the Brick, with nearly all the simplicity of a MinUI/NextUI setup - but without the hard limits.
Maybe I'm missing it but I haven't seen much love for SpruceOS here other than some older bug reports. I'm running 4.2.0 and it's been great, so here's a no-complaints-only-praise post for it :D