SteerMouse is legendary. I think it’s been around since Jaguar? Case study in getting it right the first time.

Not quite as old as I remembered, their About page puts it at 2005. But yes it's a remarkably long lasting product.

https://steermouse.com/about-us/

Funny how 20 years ago Logitech's software sucked enough for me to pay for an alternative, and two decades later Logitech's software still sucks enough for people to pay for an alternative.