Safe method for isolating the FC Mobile Beta on a second profile?

Hi everyone,

I want to try the new fc mobile beta for Android but without risking my main GSF id. A few Reddit comments mention fc mobile beta mobile then suggest fc mobile beta download and manual fc mobile beta install.

My idea: create a separate Google user on the phone, no SIM, no primary Gmail, sideload, then only allow a throwaway Play Protect token. Any other hardening? Or should I wait for an official fc mobile beta update and fc mobile beta guide?