Do you/have you tried to use Karabiner(?) Elements? I use that for easily switching between profiles for my different mech keyboards; some US layout, some UK/ISO, some with native Mac support, some without... I have the added complication of I use the ABC Extended layout (US based) so some keys aren't where I want them to be when I change keyboards. Karabiner has added some consistency to the madness!
Yeah, the older version before some major macOS change was better. It was more modifiable, and you could create your own JSON files to do more interesting things. The Elements version is still good enough though.
Do you/have you tried to use Karabiner(?) Elements? I use that for easily switching between profiles for my different mech keyboards; some US layout, some UK/ISO, some with native Mac support, some without... I have the added complication of I use the ABC Extended layout (US based) so some keys aren't where I want them to be when I change keyboards. Karabiner has added some consistency to the madness!