The G4 license apparently lives on! Halloweencostumes.com has been running pony costumes for years, and are apparently stepping into the game with their very own in-house versions going forward. Right now they have a bunch of "coming soon" items including one-piece full body pony suits, hats, and wigs all styled after the mane cast.
You can find the full selection over here! Unfortunately they all appear to be out of stock until 2023, so it will have to be next Halloween if you want to wear some. The wigs in particular would make good cosplay pieces, but look to be set for a January-March release.
Thanks to G5MLP for the heads up.
