For posterity, I can very much recommend MacMousefix. It's $2.99 to own, totally worth it to me. Open source.

https://macmousefix.com/en/

Also available via brew:

  brew install mac-mouse-fix
And on Github too:

https://github.com/noah-nuebling/mac-mouse-fix

On the fun side: can this thing help me do left-click burst in browser HTML5 games? I tried hammerspoon and other methods but nothing worked thus far.

That's pretty cool, I've been wanting something like this so I don't have to reach for the touchpad on my Mac all the time. But I gotta say, I did NOT expect to be scrolling in the Z axis all of a sudden on that site!

The site is a good example of looking good but being very annoying to use.

Is there anything like this for the MX Ergo? I would be very interested in any software-based “hacks” for the mouse.

You could also try out a Steermouse free trial, it has MX Ergo S on the recommended mice list, so MX Ero is a maybe

https://plentycom.jp/en/steermouse/

I don’t have a mouse on my Mac now (trackpad too good) but Steermouse has been around for about 25 years and I used it for many of those. Way less awful than the Logitech software.

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.

Steermouse fills this gap brilliantly. Covers every device I’ve ever tried and I have some significant exotics.

I tried this, and it's nice .. but it did let me programme all the buttons on my Logitech MX Vertical.

Holy crap, just tried this and I was skeptical, but it sold me within minutes. This truly is great!