[ecesena]

Reversible refers to the plug. USB-C is of course reversible, and USB-A also is.

There’s no constrain on the number of keys. You can use 1 device with unlimited sites, both v1 and v2, because keys are generated on-the-fly and not stored.

(There’s a limit on number of resident keys, and we supported 50 in v1, while for example yubikeys support 25. So far these are rarely used, if ever.)

[ncmncm]

I have a Somu. The docs I have found say it can only store one resident key. Is it particularly limited, vs. the Solo v1?

[ecesena]

No, it's incorrect. Do you have a link so we can fix?

Somu can store 50 resident keys exactly like Solo v1, as it has exactly the same MCU. In both there's a single master secret that's used to derive the (non-resident) keys. That's the only thing that's unique.