Can you do like
@RoyalChick did and cut a cushion donut to put around the pressure sore? I know that that isn't such an easy spot to wrap - end up wrapping around the whole body - but maybe is you are able to do that -and have it 'last/stay put' for a couple days - then a couple without it - then wrap again with cushion donut - so it ends up being roughly half the week with the donut and half the week without it - do you think that might be enough to help it along with healing??? I'm thinking wrap it, and
maybe it will last a couple of days - remove it if she hasn't managed to get it off on her own ... and a day or tow later - rewrap it with the donut? I do know she is already wary of you due to the dosing...but maybe a night time catch to dose and wrap???
Sorry, that is all I have for suggestions....other than lots of bedding. Poor dear girl, I am sure that is unpleasant - though the metacam is probably helping with teh pain from that, too - just not with healing it.
Does she sleep in a nest box, or the coop floor? Maybe you or Mrs ByBob could get a small hunk of memory foam, wrap it with an old towel or pop it into an old pillow case...put it into the nest box and cover with a bit of bedding??

I once got 'display dog beds" for free (the kind that are about 1' wide by 8" deep - just so people could see/feel what the real one would be like) and was able to put 2 together to use for my Roo a year ago when he was having those neurological problems - made him a comfier bed.