Train from Vernazza to Pisa Airport

None of the trains involved would require reserving in advance, and none sell out. So yes, you would arrive at La Spezia, take the next available train to Pisa Centrale, then the next available to Pisa Aeroporto. Just be sure to validate each ticket shortly before getting on board.

Problem is that Italian regional schedules often have a gap in the schedule close to noon, so if you were to miss your connection in La Spezia (you do have 18 minutes), it is 2 hours to the next train to Pisa and then you would be tight at the airport with less than 1 1/2 hours to make your flight. Why not take the 8:51 train from Vernazza, then you would have a back up if you missed that connection, which is short. Worst case, you have to cool your heels in La Spezia Centrale for an hour, but still get to the airport by noon.

Yes, I agree it’s safer to take the 8am train from Vernazza. So is everyone saying I don’t need to book any of these trains ahead of time?

Another question: we will be training from Florence to Vernazza earlier in the week, but would love to stop off on the way for a quick visit to maybe Lucca or some other town. Hope to do a day trip to San G and Volterra while we are in Florence. Should I reserve those trains ahead of time? Or just wing it?
Thanks!

I don’t need to book any of these trains ahead of time?

They are saying You can't book any Regional train ahead of time, because there are no reserved seats on Regional trains. You are just paying in advance and saving some time at the station.

Tickets of Regional trains purchased on line can be used on the selected one and on the next Regional making the same route. So even tight connections are not actually tight, but nothing prohibits you from making 2 separate purchases if you prefer.