I absolutely love this little guys energy and enthusiasm! Not to fond of his basic ideas themselves sometimes but his energy and enthusiasm is just spectacular! Lol. Lots of love and congrats to everyone involved in his (I'm guessing it's a he?) creation! I just wish he was somehow permanent!
I think everyone loves Shovel! And so the topic of his/her/their/its gender has come up before. IIRC, quasits don't actually have a gender or care about pronouns. They just go along with whatever their master calls them. (Though I guess they might secretly sabotage that master if they're not keen about what they're called

.)
But much as I love Shovel, I don't see how it could hang around and make sense from a plot or balance perspective. I suppose unless it became the quasit that could be summoned by Wyll or a PC warlock. And yes, I guess the infernal (or interplanar) connection might be why warlocks get to summon quasits and imps along with other creatures. Though it's pretty clear Gale has had dealings with imps before from his resurrection scene, it seems he's lost the knack.
But even if summoning Shovel didn't break balance for some reason, it'd need a lot more content to continue to be as great. Personally, I think it should go out on a high and be remembered fondly. I just want Shovel would get a proper goodbye if it survives until the next time the player does a long rest, rather than just vanishing. A short scene with it on returning to camp that night, in which it gave some snarky reason for doing a runner would do a lot to give me some closure!