I noticed quite a lot of people confused about everyone having installed the new Boost, while their play store doesn’t do anything and just showing their Boost app registration.
You need to follow this link, NOT go to Boost itself:
https://play.google.com/apps/testing/com.rubenmayayo.lemmy
Boost is in a beta phase, so if you want to install it and test it out so you can inform the dev (you can do that in this community), then you can follow the link and install Boost that way.
Hope this helps. The above link was tucked away in the featured post, pinned at the top, but it seems to have been overlooked by some of us.
Enjoy and have a great weekend :-)
Also helps to clear the cache of the Play Store app and force stop it and open it up back again to see the change.