Star Trek: Picard certainly sounds like an interesting series to me, especially since it's set 20 years after the events in Star Trek Nemesis, if I recall correctly, Nemesis was set during the Voyager era because I think Janeway had a cameo in Nemesis as an Admiral which means Picard is set post-Voyager.
I'm certain Seven of Nine knew about Picard because he was formerly a Borg and I'm certain when Seven was a Borg in Voyager, everything about Picard was already part of the Borg Collective meaning all Borg would have the knowledge of Picard, I'm thinking within the 20 year period between the events of Nemesis to this Picard series, Seven of Nine must've met Picard within that time period, I'm guessing there might be possible flashback scenes showing Seven first meeting Picard.