[lproven]

> I soon realised that three-button mouse chording isn't doable in this decade,

The scroll wheel on any wheelmouse is a button and you can click it as well as spinning it.

All wheel mice are also 3-button mice.

[rcarmo]

Try doing that on a trackpad--but if I wanted to use a mouse, the chording is too cumbersome.

[lproven]

On my work MacBook Air, I installed a FOSS app.

https://github.com/artginzburg/MiddleClick-Sonoma

Works well, but I miss the physical middle button on my Thinkpads.

The chording isn't really cumbersome, just unfamiliar. You get used to it quite quickly with a few tens of minutes of practice.