Volvo made front and rear mud flaps and they are still available new. They come with a choice of screws (slightly longer than the existing) or rivets for fixing.
https://www.skandix.de/en/spare-part...sides/1020841/
https://www.skandix.de/en/spare-part...sides/1020846/
Skandix raised their delivery charges to the UK earlier this month so might not be your best source unless you’re ordering as part of a larger batch of stuff.