It was very affordable (sub $20), came in lots of colours (including this lilac colour that I love!), and is super comfortable too. The vertical mouse I used previously, a Ugreen one, had a narrower grip that was less than ideal.
The mouse is by "Sanwa Supply", model number "GMAERGWBT22V" (V for violet I presume, it shows up at just "BT22" when pairing with Bluetooth), though I'm sure there are plenty of identical models from other brands.
The plastic finish is nice and will last a long time, as there isn't rubber everywhere like on the ridiculously priced MX Masters. The buttons are silent and have a nice click, the side buttons for forwards/backwards are nicely placed, you can switch between 3 devices (two Bluetooth, one with the dongle), and the scroll wheel is nice (though not a metal one)
The mouse came with a magnetically attached wrist rest too, which is nice, and even without it, it does not suffer from the trailing pinky finger issue of other vertical mice. The magnets are strong enough where it isn't super loose but not too strong where it's hard to detach. It's a nice bonus when I'm at my desk for long hours, and it can be removed if I need to pack it.
BUT one of the main reasons I bought it, aside from the fantastic colours, is that you can use it with a AA battery! No glued in nonsense, it's super easy to swap it out, and the dongle is also stored in the battery compartment too (always a nice bonus). I use it with rechargeable IKEA Ladda batteries, and it's been awesome.
Its a bootleg MX Vertical. Better off investing in a Logitech MX range tbh. Had mines for a decade.
Unsure why OP thinks they are ridiculously priced... Actually worth every penny.
You can swap the battery and the older ones had a flaw with the thumb button, but it's repairable. Software is well supported on everything and opensource drivers exist so it doesnt matter if Logitech kills support.
Vertical mice aren't a Logitech trademark. The shape is noticeable different from the MX Vertical, it has the cool wrist rest magnetic thing, and the angle it sits is different. The colours are a lot nicer than the graphite black of the MX Vertical. Also, the MX Vertical (at least the current revision) does not use replaceable batteries.
Logitech Options doesn't support Linux, so no, it's not "well supported on everything", though there are community made alternatives that seem really neat! I imagine the mouse itself does, but nearly all mice should work on Linux so Logitech is not unique in this
The MX Vertical is over $100, over five times the price of this cheap little guy, so I don't think the price is worth it, especially since this cheap one has fun colours + a more comfortable shape for me (YOUR HANDS MAY VARY)