That's cool! I only really do thumb-ball mice, though, and I haven't really seen alternatives to Logitech in the same form-factor. I imagine they might even have a patent on it.
Buuuut I'm betting I can do stuff like repair the couple of MX Ergos I have lying around if I need to if I get motivated about it. Or like, maybe there's a way I can have replacement parts fabricated or use the shell of a Logitech mouse as the basis for something similar.
You hear that Logitech? Charge me a subscription fee and I will absolutely figure this out and distribute blueprints and repair guides to the whole ass internet. I appreciate your ergonomics, your unifying dongles, your precision mode, and all your hotkeys, but $90 is plenty for a mouse. Don't get greedy or I will personally bite you in the ass.