Epic already did this at the height of fortnite's popularity, by using a "fortnight installer" app that you had to get from outside the play store. Can't remember why they backtracked, or why they didn't offer store/sideload versions at the same time.

Google even took steps to prevent people from installing malware pretending to be fortnite, and steered them to the official installer. Not out of the goodness of their heart, TBF.