2. I always tend to the latter in this cases. We never know if these companies will be around in a foreseeable future, so take it with a grain of salt and assume that support will eventually end. Being closed sourced adds an additional vector to the case as the community wouldn't be able to continue (unless of course they decide to open source it before (if) they close).
Not surprising they only support Windows and Mac OS. While Microsoft put some effort for backward compatibility, it doesn't apply to Apple. Although people always could try run older OS on VM and perform USB passthrough as workaround.
PS: Password limited devices are always a double edge sword - I always remind of this man[1] that isn't able to access his stash of ~7.000 bitcoin. So whatever users end up deciding for sure keep that password somewhere safe.
[1]https://secuxtech.com/community/how-it-works/forte-usb/safety-guide
[2]https://www.bbc.co.uk/news/technology-55645408
I also did quick check and doesn't find any mention of internet requirement. And i agree such device is double edge, with more disadvantage to the owner assuming only the owner know characteristic of the password used for encryption.