Ooh, thanks! I blindly type c-x 8 RET, then finding myself stumbling through 9 different entries for Phi, but I hadn't explored the prefixes. I just realized I could create a custom which-key entry-point with my favorites in a prefix.

Also just learned about compose key apparently, and I noticed that I can program this split keyboard I'm using to turn that into a chord, anywhere!

Then an LLM told me that I can 3D print my own custom keyboard with 32 programmable layers. Everything is an infinite rabbit hole these days, how wild.