Letters From A Universe-Jumping Demon Space Pirate

Sandor "Sniper" Masonard may have escaped from a truly despicable post-apocalyptic living situation, with even more morally bankrupt family-members chasing him down about it, but just because he's free of his home dimension doesn't mean he's out of trouble. In fact, he barely makes his way through a single dimensional portal before he's kidnapped by inter-dimensional space pirates! Granted, they are very polite space pirates with a very dashing and mysterious captain,  but that's beside the point. Can Sandor charm, cheat, shoot, and science his way to a favorable outcome for both him and this ragtag crew of interstellar fiends? Or will he be forced to go on the run from even the other inter-dimensional outlaws?

And will his dearly beloved aunt ever actually reply to any of his multiple letters asking for advice?

~Spoilery Trope Summary Below for those who want it~

Epistolary Science Fantasy novel; Male Demon Protagonist slowburn builds his space-army through the power of found family and {space!} {media} piracy, falls in love with the nerdy Possessed Human pilot, starts an inter-dimensional war, and confronts his homophobic mad-scientist cousin. In that order.