I was finally able to use my scanner today (and learnt some details about nixos and sane by the way) !!
First, I always thought I was using “airscan” driver with the configuration from the wiki
hardware.sane.enable = true;
hardware.sane.extraBackends = [ pkgs.sane-airscan ];
But I learnt that there is also a escl driver in sane-backends, and I was using it anyways … see this ticket
It seems that there is no way to manually choose the airscan driver over the escl driver …
I tried to explicitly disable it with:
hardware.sane.disabledDefaultBackends = [ "escl" ];
And bingo, now my scanner uses the airscan driver
And luckily the airscan driver works properly with my printer/scanner
Thanks @symphorien for your help on this