but it seems that you need to at least solder the keycaps yourself, which I can’t.
solder ... keycaps? Surely you mean switches :D
Anyhoo, Moonlander? https://www.zsa.io/moonlander/ - hotswappable switches, ortholinear-ish, split and qmk support
edit: or bit more minimal: https://www.zsa.io/voyager