Have you come across The Black Hack at all? https://the-black-hack.jehaisleprintemps.net/english/
It uses a 'roll under your stat' mechanic which means it works well for solo play.
Viewing post in Ideas for a gamebook-oriented rule system
No I hadn't, thank you very much! Will take a look. Yeah, "roll under your stat" was a staple of gamebooks back in the day. Wouldn't work for me though, because I want the same dice pool mechanics that worked so well in my previous game.
Edit: that said, The Black Hack is using one of the methods I considered to determine which attributes to roll for each action. I'll follow this trail for a while then!