Not the cheapest thing ever but I think I should ask if you have seen those crawling habit training restraining booties? They are like the best way to make you crawl, I am pretty sure you can be forced in to a crawl by adding a lot layers but its not the most comfortable (or realistic even if it is cheaper I the moment).
This Restraints item by StraitJacketShop has 4115 favorites from Etsy shoppers. Ships from Poland. Listed on 16 Apr, 2024
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(side note it might look painful and it kind of is if you dont crawl/ try to stand up but I have been told it's not noticeable and that they are pretty comfortable outside of trying to stand up)