but isn;t a single address how these hardware wallets work? im way more nervous about having 50 different address and key pairs and losing 1 or more than keeping up with and securing a single address and key pair. but again, im trying to figure this all out and not lose any coin in the process.
Bitcoin core wallets are deterministic wallets, meaning that all key pairs are derived from one seed. Therefore, you only need to back up is the wallet file and every time you restore that wallet you will get the same addresse. So, you don't have to back up each key pair individually.
so i can test the wallet backup in btc core without having to have a second computer running core?
Yes, just open the back up file and see if you get the same wallet.