HD wallets are good wallets to use for storing your bitcoin and broadcast your transaction without leaking private keys online but to use it well and safely, you must start with good practice of purchasing your HD wallets and backups.
HD stands for "Hierarchical Deterministic": it's a wallet that derives all new addresses from one "seed". It doesn't have to be a hardware wallet.
How do I achieve the same sense of 'security' with an HD wallet. It doesn't seem it's that simple any more. Sure, I can backup the data itself, but I want the assurance of a text based backup. Data formats change.
You could keep a copy of the software (Bitcoin Core, I assume) with your backup. But I get your feeling of being uncomfortable with modern wallet, and for the same reason I haven't switched to a descriptor wallet yet. It feels much more like a black box to me than simple old-fashioned private keys.
Just a thought: you don't have to switch to a new format. If you like your current legacy wallet with legacy addresses, just keep them. Or only move small amounts to a new wallet for daily expenses.