I have not measured by micrometer, but it is slightly longer than 22mm. I was able to find inexpensive watch bands for it by searching for Vivoactive 4 watch bands. If branded to fit that watch, there is an excellent chance it will fit this one (and the two I have purchased to date have fit it). Vivoactive 4 and Venu 2 have essentially identical case dimensions, so case covers/screen protectors should work as well.
I have 2 different Archer bands (bought on Amazon), 22mm size, and they both work on the larger Venu 2. I agree the Vivo4 bands should fit but as you said it appears to be slightly more than 22mm so not all "standard" bands will work.
