Given SEGA promoted that song more than this, it's making sense people though it was, but no, this is the main song.
Given I find theme songs somewhat represent Sonic in his current mindset of himself and the adventure, it just sounds so.. I dunno, like the frontier means not just where he's going but who he is, that he's coming to realize himself or something. I mean, I doubt SonAmy will be a legit thing at the end but given he's directly saving Amy (and Tails) as the "ones I love" where he usually just mince words to refer to them as good friends. I dunno.
The more I learn of Sonic Frontiers, the more it sounds like aliens got a hold of Sonic Generations and with what they know about our worlds culture made this game for us.