When you use the Gmail app on iOS, and receive an invitation to join a new album, the current sharing link is not tappable. I did try to put this in as an anchor tag in HTML, but this does not work.
This seems to be a known issue with Gmail:
One possible solution to use Universal Links with iOS:
This does require some non-trivial setup, however. For example, you have to host an association file on your own web domain and that must use https:
Since this web domain will be exposed in emails, it should be specific to the app. So, using universal links would require setting up SSL for an app specific domain. All because of an apparent issue in Gmail. Yark.
And it seems there may be problems with universal inks with Gmail in any event:
It does look like some hacking might work around this:
It is also possible to use services like branch.io