Good morning from here, Judy

And congrats on your new friend, they are famous for stealing hearts
Glad to hear he recovered so well. They grow quickly so your 10 gallon will look small soon, but since you're planning on an appropriate tank after moving I reckon it will work somehow, just keep watching your water quality, they are messy fish.
Oscar can be picky with food, especially when used to always the same, but you're right in trying to offer him different stuff. Mine won't eat (thawed) shrimps but can't resist an earthworm or nightcrawler. Still think he would eat shrimps if it was all there was, but if yours eats pellets (well a certain brand) at least you can take your time with trying out different things.
Have fun here and just ask whatever comes to your mind, lots of helpful articles here too. Cool job btw, can help you lots probably with fish keeping