Cherry has had low profile switches for a long time, though they are far from common.

https://deskthority.net/wiki/Cherry_ML

I have one G84 and it's nice and "silent". But it's a pain to find compatible keycaps:

https://deskthority.net/wiki/Cherry_G84_series

The problem with those Kailh is getting keycaps. At least the cherry one will be compatible with MX keycaps, although I don't know where you'd get low-profile ones from. Hopefully they're available as spare parts soon.

As an ergodox user, I'd also be really interested in a mobile low-profile Atreus, but I need more keys, at least like an Atreus64.

There's an atreus62 variant available (I have one, love it). You can order the components (or prebuilt models) from profetkeyboards.com

Personally, I shift the letter keys out to the sides by 1, so the pinky's only have 1 column to deal with, and there 2 extra rows in the middle. This also has the effect of rotating the wrists outwards even more - comfy!

As it turns out, I don't even need the full 62 keys (and have even pulled 8 keycaps off!). Depending on your preferred layout, you might also get away with <60 keys.

But a low-profile variant would be nice :)

Oops, I actually meant atreus62.

But maybe an atreus64 would be better (if it existed) because I would like some more thumb keys like my ergodox.