also being able to refund point shop items even if we only get 50% back or nothing back would be great

Not going to happen.
Deleted items will eventually lead to support tickets from those that either "accidentally" deleted one, or their account got hijacked and the hijacker deletes them all.
Gems would give stickers, and other point shop items, a monetary value, something Valve doesn't want them to have.
Point shop purchases are an 'all sales final' (mostly) transaction. If you want new stuff, Valve wants you to earn more points by buying more games or creating content that people feel like awarding.