MicroG devs are working on fakeing play integrity api since 2023: https://github.com/microg/GmsCore/issues/2050
it seems that play integrity continue to change internally day to day... He is waiting that google stabilize it. Then will be a pull request.
They love to do this. 2 years ago they renamed Office (the online, browser based version) to Microsoft 365 https://www.computerworld.com/article/1614302/office-to-be-rebranded-microsoft-365.html
They can present the "new" apps to shareholders