Its rather difficult and time-consuming to apply, interview, and compete for an ANG pilot slot...let alone the 2+ years of training you go through, AFTER going through the whole medical process and getting assigned an AMS date. To be competitive for an ANG pilot slot you'd better have a good GPA, a stellar resume and a much better reason for joining than "I got terminated from a regional airline after two days" or "I heard Uncle Sam has a really sweet flying club!"
The only fractional you'd likely be remotely qualified for is Planesense/Alpha Flying...and they wouldn't look kindly on somebody bailing after 4-6 months to go fly an RJ. Also not sure you'd be able to afford the pay cut at that point...
Sorry to sound negative, its not my intent. You'd be better served going to another 121 operator, or if there is a delay there flight instructing until you have enough time to go 135, either as a passenger turbine FO or for a company like AirNet.