I store mine on DVDs or USB sticks.
USB sticks are not recommended for long-term storage. They may be unreadable in a few years after they are written.
Always a good idea to have important files backed up on at least three platforms / types of media. For example, hard drive, CD or DVD, cloud, etc.
Oh, and print. Paper is not device / programming dependent.
btw - where is the “Rosetta Stone” for digital info?