Hi, will it be possible to connect multiple Steam accounts or list games available through Steam family sharing?

so far it's not possible - there is a wishlist entry by CaptNeo here though - https://www.gog.com/wishlist/galaxy/integration_of_multiple_accounts_per_platform

and we also got an older thread created by my covering that matter so feel free to join us there :)
https://www.gog.com/forum/general_beta_gog_galaxy_2.0/feature_request_add_multiple_instancesprofiles_of_the_same_launcher_eg_add_steam_twice

no it will never be possible without custom 3rd party addons because Gog can't do it

I mean, if that is not possible officially, maybe they could allow GOG Galaxy to include Family shared games. I have two steam accounts, one is really old, and I kinda forgot about it for a long time until my grandfather found it in his account notebook. So now I just Family share from one to the other.