Multiple users on tablet

Hi all.
I’ve just flashed eOS to a tablet, which I will share with my wife, not yet accustomed to the bright side of the force.

I managed to add an user to the tablet, but it seems that only one administrator is possible and therefore the simple user cannot install apps on her/his account.

I installed Fdroid on my (admin) account but I was not able to install it on the other one. I was warned to accept all the risks. but eventually ended aborting the installation.

After looking around the net, I understand that G apps are meant to be “personal” (how different ?) but I’m wondering if would be possible - in this OpSource environment - to install apps for all the users on the device.
For example, say, OpenBoard or TrackerControl