Building the mouse Logitech won't make

My favorite mouse is the Logitech Anywhere MX. It's highly comfortable despite being pretty small. The back/forward buttons on the side are indispensable for web browsing, file management, and switching weapons in first-person shooters. It takes two AA batteries which last for months and take seconds to swap out. The dongle is small and has good range. The scroll wheel switches between clicky and free-scrolling.

It's pretty much the perfect mouse, IMO, to the point that I built up a back stock by hoarding new and open box on eBay. But there are two main problems:

1) The the microswitches go bad after a couple years. It's possible to replace them, but it's tedious and you run a very real risk of damaging the PCB (as I have already done).

2) The dongle is USB Type-A only. Logitech actively refused to make a USB-C unifying receiver. I assume they wanted to shift to bluetooth but they still made unifying receiver devices for years and years after bluetooth was everywhere, so I dunno.

As far as newer iterations, the Anywhere MX 2S is somewhat tolerable, but it has a built-in battery which must be charged every couple of months, which is annoying. All of the newer Anywhere MX mice are even worse because they changed the basic functionality/features of the mouse with each revision. Oh, yes and they cost $90 (!) retail now.

So basically one of my side-projects, one of these days, is going to be to try building an open source Anywhere MX clone. Should be a fun yet challenging endeavour. I know there are a bunch of online communities making their own keyboards from scratch and at great expense, is there such a thing for mice?

I'm on an MX Anywhere 3S and overall I'm a fan. The killer feature for me is the Bolt receiver being able to pair to both the mouse and the MX Mechanical Mini keyboard and being able to have a second receiver that both devices can switch to. Unfortunately they have to be switched over individually rather than following each other (and the mouse's switch button is underneath), but still, this is a pretty killer configuration that I haven't seen offered elsewhere.

For clarity, I plug my main receiver into my workstation and use Synergy to take the M&K over to an adjacent laptop in software, but the secondary receiver is useful when testing installers for NUC, Jetson, etc. Basically I've got a bare metal device on my desk plugged into a mini monitor and with one little dongle I can trivially get my keyboard/mouse on that device including in a preboot environment like the EFI firmware.

ist that the whole point of unifying recovers as well? or am I missing something?

Unifying definitely lets you pair multiple devices (keyboard, mice) to the same dongle, but I'm less sure about whether it lets you pair multiple dongles to the same device(s) and then hot switch between them.