(Don't know why it took so long for me to reply to this) Yeah, I've definitely had characters/worlds where I hyperfocused on them for a period but Rose Cross Descendance (the name of Tresor's band and also the whole "series" he belongs to) has definitely received a good chunk of worldbuilding.

Exhibit A: bsky.app/profile/soni...

Exhibit B: bsky.app/profile/soni...

And Exhibit C: bsky.app/profile/soni...

This isn't even getting into the stuff I *haven't* posted about on here, such as the Alternate History shenanigans.