I have something like this that I used in my RV when I tore out the old bathroom: https://www.amazon.com/Profile-Assembly-Perforated-Strainer-Replacement/dp/B0BZBYS19J - Just a thought - also the sub flooring if it's not tile will be soaked, you are correct, but if it wasn't for too long it can dry out and still be functional.
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You can re-putty the drain fitting for a better seal but the flex will require some kind of support or it will work itself loose again given time, even with a flexible coupling. Moving parts tend to get looser over time.
If it's a broad drain, you could probably try to remove it, use the gap to add something underneath the pan and then close it back up? Or if the crawlspace has better access, you could try to do the same from below? You need to get a peek under the pan to know how easy/hard to fix it might be. Empty space could be fillable. Extant but soft bedding would have to be removed before adding something solid.