It is not a impossible task, but you have keep in mind that if he serious about founding his own political party and have their own congress people candidates to run for the mid term elections then he will have all the media machinery against him, the democrat party is already critic against him and then he will have the Republican party against him as well, that means his political message will real completely on social media and Twitter/X, which he owns.

Anyways, the political scenario in the USA is already deeply controlled by their duopoly on politics, that even if Musk managed to get some seats in the congress and in the Senate, it would be quite unprecedented as nothing like that would have never been imagined to happen in the modern history of the country. Both the Democrat party and the Republican party have tightly held power and elections in the lastest decades, they are not willing to allow that to change any time soon.