Maybe you'll find my post https://arathunku.com/b/2023/moonlander-keyboard-layers-tour... helpful with oneshot modifiers across layers but also keeping Shift and Ctrl accessible. I really hated any timers / held vs tapped on home rows, it prevented me from fast typing and rollovers. Now I really only have space bar on hold/tap that's used in usual writing but it's on my right thumb and have never been a problem.
I'm currently working on a tool to help with code reviews queue - automatic reminders, single queue list from multiple teams and more. At the moment it works only for GitLab because that's what I needed for myself. If you had used https://pullpanda.com/ with GitHub, you will definitely know what's this about.
No production website yet, but I'm already using it daily. I need to deploy it to heroku and release a version that can be usable to others. If you'd like to try it out, please reach out to me here or on twitter @arathunku