FWIW, I started playing with something that felt like more of an 'app' experience with Beancount with 'Beancolage' so you could have plaintext accounting integrated alongside a reporting UI: https://github.com/seltzered/beancolage

It's still an early concept though, but at the end of the day it's a vscode-like experience so aspects like git are just an extension away.

It's for the UI, yes, since they're not my accounts, I'm just tech support for them ;-) I've seen there is an hledger-web, but there's a bunch of reports and workflows already set up in Gnucash and switching would involve learning new things and I'd rather spend as little time as I can on accounting and taxes. (OTOH adding a script to enable "git log -p" took like ten minutes.)