Use a hardware wallet -> You will link your device without exposing the seedphrase. Any transaction you make will need to be authorized from the physical device itself. This is basically the same as using the device's software (such as Trezor suite or Ledger live).
"I already have a seed" -> You will be restoring your hardware wallet (or any wallet) into Electrum. Doing so would make the device pretty useless afterwards.
OK, so it's just a matter of the computer knowing the seed when I enter it manually?
Could I still sign on the hardware device?
I will only use Electrum on an airgap computer, so it makes no difference whether the seed stays on the device or I enter it manually on an airgap computer.
I would like to use the hardware wallet (Specter Shield), unfortunately it is not compatible with Electrum, but if I enter the Specter Shield seed manually into Electrum, I could still use the Specter Shield as a signing device, right?