I would have to go back and rewatch, which I probably won’t, but I feel like between Rebels and Clone Wars they pretty much filled up all of the time gaps with Maul so I’m not sure where this could be set or how interesting it could be plot wise, but I’ll def check it out.
IIRC, it's close to 10-year timeline gap between the end of
Clone Wars when Maul escapes from Ahsoka & the post-credit scene in
Solo when we first see Maul again, having once again reestablished himself as a leader in the criminal underworld. After
Solo, it is another 6-8 years or so until Maul reappears to Ezra outside the Sith Temple on Morriban in
Rebels, having lost everything. So aside from the one brief check-in over a 16-year period, we don't really know any specifics about what he was up to during the "Rise of the Empire" period. I think there is a good amount of story potential there.