And even if what was Mando Season 4 is condensed into this movie which is unclear, there's still the issue of Ahsoka Season 2 as you said, as well as any other "Filoni-verse" shows that might tie-in between now and release.
I fell off Mando after S2 (well really BoBF), and I know I'm not the only one. Regardless of whether or not these characters are widely recognizable. As The Marvels and other Marvel films have shown us, if general audiences feel like they need to do TV show homework to understand a movie (in this case, what these familiar characters are doing in the movie), they're not going to pay theater ticket prices.
Marketing needs to ensure two things. 1, audiences know or are at least led to believe that's not the case. And 2, that this is bigger, better, and more cinematic than its TV show counterpart or at least lead the audience to believe that's the case.
Fail to do either of those things and this thing is DOA, familiar characters and all.