Thank you for your response sir. Just to recap: Sparrow (or any BTC wallet with sub-account support) does allow the user to create a second account even if the first one has never been used.

Next time in order to restore the wallet from scratch I must either recreate the second account or modify the derivation path manually (depending on the wallet settings / UI)

Please do let me know if I'm missing something. Thank you again for your time and support.