Sorry, I just realised my comment was ambiguous. The apps claim not to support Firefox, and then I'd just close the app without trying with a spoofed UA - so it's not necessarily a technical issue.
The only one I have bookmarked is https://getmibo.com, which claims to "currently only work in Google Chrome"
The only one I have bookmarked is https://getmibo.com, which claims to "currently only work in Google Chrome"