You are absolutely correct - if we are going into that sort of detail then the legally required paperwork ............
RCD Certificate or proof of exemption
Insurance in the 'local language' for the countries visited (Different countries has different insurance reqirements, if I remember, Greece is £5m, whilst Italy is £3m
Proof of VAT paid certificate
Passports for everyone aboard
Certificate of location on 31st December 2020 (Brexit)
Ships registration documents
VHF licence for the boat
VHF 'operators licence' for the radio operator
Some countries require certain qualifications from Skippers.
You'll need to check the following situation as we have not sailed in Europe since 31st December 2020 (Brexit)
Remember you can only stay in the EU waters/countries for 90 day in 180 days - you'll need to go across to the North African coast for the other 90 day before you can return to EU waters/countries.
Presumably (unless you have a water maker) you'll be going ashore somewhere every few days for water / food and fuel.
We were refused insurance if we planned to cross the Bay of Biscay between October and 1st May (and thats for a Cat A boat with a Yachtmaster skipper with 1000s of miles experience).