You've got
Monterey dome with slider in some Monterey keyboards.
I've seen similar sliders in keyboards that are not identifiably from Monterey; whether those are Alps-mount like Monterey's, I don't know. It would be interesting to see the FCC ID, the bottom of a keycap, and as many other details as possible. It could be a Monterey OEM, or someone using a similar design, or even someone buying in some of the same parts from whoever supplied Monterey.