My understanding Is that an OS on the SD Card takes over the EMMC, so should allow easily to have multiple OS on the go (at least, it works on Pinebook Pro, duknow for the legacy one).
And, an extra 2p, a cheap Andro*# phone would not have kill switches or the option just highlighted

Seems they have something running?:

Maybe they can provide updates here

Interesting interview here, on that topic: https://www.phoronix.com/scan.php?page=news_item&px=Zlatan-Todoric-Interview

You should be able to do so using the SPFlashTools (as here from Android to Ubuntu: https://forum.fairphone.com/t/fp3-fairphone-open-os/52301) but you will need to find the original Android scatter and associated files...

@normandc Same here but noticed i need to start Dekko first before sharing files fwiw...

There is a thread on the Fairphone forum stating Open OS will come later: https://forum.fairphone.com/t/fp3-fairphone-open-os/52301

@normandc Once you have the checkboxes displayed in the Contacts, there is an icon Top Right that can be used to select all Contacts fyi

GPS never worked for me on FP2, there is a related open issue here fyi: https://github.com/ubports/ubuntu-touch/issues/356

@baruchiro You may have to create the folders in /userdata/system-data/var/cache/... i do not recall if i did or not on my side

@baruchiro Adding this line will allow you to mount that /var/cache/.. folder inside the larger /userdata partition so there is space available to perform the package installation (double slashes are expected, check similar existing lines in /etc/fstab and note it's a bind mount)
Not sure if such change should be made persistant or only considered as a workaround...