Next from discussions with Stpehen I've sort of figured out that we need a
config mapping table of sorts and then a means to activate entries of that table
at runtime. I'm trying to come up with something for this.

Good to hear this.
I did not catch up your steps before, so I did not give much comment on the pinctrl core.
I would try to do it if I can now.

Regards
Dong Aisheng