If you have a hardware wallet (I use a trezor with electrum), the wallet won't load up unless the trezor is plugged in so something must be done to decrypt the wallet (even if it is a public key on the device or an initial unique certificate associated to that seed maybe at an odd derivation path - using symmetric encryption).
That's actually interesting because it does not apply to my setup. When I open my wallet, the following message box is shown.
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When I select 'No' or simply close the box, I can see the list of all transactions. Everything looks as if I were using a watch-only wallet.
Edit: I quickly found out that I can enable the encryption manually just like in a normal Electrum wallet.