The app is still an alpha, so you sort of already are? It’s all open source so you can explore the git repository, report bugs, or build it yourself if you really want to.

Click on the version in settings -> about. You’re already an alpha tester. If you want to get more bleeding edge, you can build your own binary from the GitHub sources and sideload it.

If there’s a daily build, I’m not aware of it. If there is one, I’d expect it to be considerably less stable than most beta programs though. It would be an unstable dev build rather than a stabilized beta invented for non-technical testers.

The whole software is currently considered alpha. If you want to test bleeding edge stuff, you could build the main branch locally and test that. Or you could use the app releases and report bugs on github (the devs would much prefer pull requests fixing bugs than just reports and they’re great at merging). I’m not a dev but I have contributed to the app.