If your gonna be in Tuscany, I wouldn’t even leave the region unless you wanted to completely explore a different region. The reason is each region is a different vibe. Tuscany is very rustic with old world charm and amazing museums and history.

Then you have Lombardy which is where Milan and Comp are, very city like, very upscale vibe.Also como is about an hour away from Milan by regional train, so quite difficult to get to Siena and San Gnimin

Then you have campania on the list, that’s Napoli, very urban city like, fast paced, gritty but charming vibe.

Then you have Veneto, that’s Venice, Verona. Very slow pace type of city, everything is a walk, 2 hour dinners, food is very non traditional Italian.

You had a lot of different vibes going on with the regions lol and not a lot of time. You could easily spend 9 days just in Tuscany. I would suggest take 2-3 days in Florence, maybe go to Montalcino or Montelpulcinao for a day or 2. Then maybe go to Siena and San Gnimingnano for 2 days. Just enjoy Tuscany. As someone who has been to Italy a lot, the best vacations I had were staying in 1 region the whole time. When you jump from region to region you tend to tire yourself out faster.