I've got a few SoloKey. This project seems like a joke comparatively as solo is actually open source hardware[0] and this is not. You can look above to see how OnlyKey might be more trouble on the software side than it's worth and potentially is just a liability.
I've got a few SoloKeys too. The USB C one broke in half and looking on Amazon reviews this is an issue for lots of people. Meanwhile my OnlyKey has been running strong 3 years in and has been on my keychain the whole time. Also SoloKey doesn't manage passwords at all, while OnlyKey does.
But it's not open source. Why even bother to call it open source if it's not? Since the Solo is open source hardware if you don't like it, you can change the design and get your own boards cut on OSH Park.
[0] https://github.com/solokeys/solo-hw