Long time lurker, first time poster (hi, y'all)
Synopsis was out long time ago. Read here. There are a lot of details on showrunners' twitter pages regarding the show, which would take ages to dig up, but I myself saw stuff that seem to point out that the series is canon to the games. I would recommend watching an YouTube video on the topic, because I'm sure that someone was keeping track of all that information.
That's actually possible that this is the case. I've seen on Twitter somebody ask one of Prime's show runners whether they are involved in writing for other Sonic projects. One of them said that they can't talk about it. Unfortunately, the twitter account that asked that question was deleted, but this guy on Tumblr can confirm that was the question asked. If the showrunners weren't involved with any other Sonic projects, they could have said no explicitly 🤷♀️