Up.
I did 6 clean install today (without SIM) as said here (in French)
This … app does need a gg account on the phone and then Aurora (anonymous mode) to install.
While login to an existing SNCF account, a toast notification asks to install a webbrowser with a Play Store link (which opens in Aurora). Firefox, Opera, Edge and so one… but no Icecat Mobile nor FOSS browser… I’d choose FF and then app works (login and all features).
Removing gg account (Settings > Accounts) is possible, app works. Works too after Firefox been removed, but no more log out is possible.
Perhaps other apps (bank) will need same install…