I just got mixed feelings about a TV series based on the Sonic movies. Don't get me wrong I would love to see what Tom and Sonic get up to on their down time... but given Knuckles is the only announced character for the TV series it's believe the show will be for Knuckles and I'm like "I'm all for spin-off shows for side characters but Marvel Cinematic Universe didn't do that until Phase 2!"
I also have my concerns on what will happen once Sega and Paramount "burn out" with Sonic's film series. Like what happened to Indiana Jones, Pirates of the Carrabean and Resident Evil films. This is why I go on about a "Sega Cinematic Universe" Sonic films are the basket with all the eggs in it when Sega should consider turning other Classic-era game franchises into more baskets to carry those eggs in.
Strike when iron's hot.
Sonic is gonna popular this year thanks to Sonic 2 movie, Sonic Prime, and Sonic Frontiers.
There's no guarantee that it's gonna be like this two years for now,
so It'd make sense to go full power right now,
That's what Project Sonic 2022's goal is.
And about why pick Knuckles...
TV series is very limited on budget too, that's why they usually pick a character that's not main character
It would be too expensive to make Iron Man or Captain America TV series with Robert Downey Jr or Chris Evan.
That's why they chose Loki, Hawkeye, and Falcon & Winter Soldier for TV series,
and even that's still expensive as hell.
It's a risque bet.