Historically, Republic has been quick to support newly released Google Pixels. That said, Republic has yet to announce support for the recently released Pixel 5a. It may also be worth noting Republic is in something of a transition phase:
Please understand, like most answering here I’m not a Republic staff member. I have no inside information to offer regarding what changes may or may not be coming to Republic or when such changes may or may not occur. I also do not know to what extent, if any, forthcoming changes might impact addition of new compatible phones.
Candidly, the bottom line is until and unless Republic announces otherwise, one should presume any phone not listed on Republic’s roster of compatible phones is not supported. If/when Republic has something to say on the matter, generally, it would be said here: Announcements & News - Member Community