Yes hardware wallets are definitely good options when you want to hodl for a longer time when seeking for hardware wallets use Trezor and avoid the ledger wallets for now because some of their new policies regarding ones seed phrase sucks. You can also try out the new passport hardware wallets.

Another way to safely store your bitcoin on offline storage is using an airgapped device for storing your bitcoin. This doesn’t require any purchase of hardware but the device that is to be used for offline wallet creation with electrum should be one that has never gone online before And will never go online.

Your monthly purchase of bitcoin is certainly one of the best idea to accumulate bitcoin, it is just like you’re doing monthly DCA, this will help you minimize the risk of losing and also maximize the profit.