In the Play Store, when looking at an app in the upper right corner you can hit the three vertical dots and unselect ‘Enable auto update’. (At least on my flavor of Android.)
The downside to this is that you need to remember to update it when there’s a new version, but if you look at the app details you can see if it’s early access or production. So you can wait out a production update until the next early access is released.
An additional downside is it will block you from clicking the ‘Check for updates’ button in the play store for other apps until Roon is updated.