Florence and the Basilica di San Miniato

Here is what one source says:

https://www.visitflorence.com/florence-churches/san-miniato.html#:~:text=You%20can%20also%20catch%20the,lead%20up%20to%20the%20church.

How to Arrive

Since the church of San Miniato is located just outside the city walls it takes a bit of planning to reach. It is easily accessible by foot, car, bike (for those who like to climb) and by bus. If you like the idea of a panoramic hike, taking in the green hills that surround Florence and the spectacular views of the skyline, then your best option is to walk up to Piazzale Michelangelo. You can follow several paths from either the Piazzetta of San Miniato or the path behind the Torre di San Niccolò. Once you are at the panoramic terrace, climb the remaining steps to the top of Via delle Porte Sante to arrive at the door of the church.

If you have a car, just follow the signs for Piazzale Michelangiolo and you will find parking either in front of the church or on the street that leads up to the church. Be forewarned it is paid parking from 8am-8pm. Cyclists (and walkers) can follow the same path as the cars, there is a well-kept sidewalk.

You can also catch the ATAF city bus #12 or #13 from the center to get to the church, there is a stop right in front of the stairs that lead up to the church.

Here is another source:

https://www.feelflorence.it/en/points-interest/basilica-di-san-miniato-al-monte

The access by car is possible from via delle Porte Sante. The disabled may get in and out of the car on the gravel square in front of the church (there is a parking area just a few meters away).

Access to the churchyard is possible through a short and steep ramp. At the entrance of the church there is a big step that can be overcome thanks to a mobile ramp (please inform the monks before your arrival in order to use the ramp).

Theoretically. Look on Google Maps Street View. As mentioned, Limited on street parking. . Be very careful to avoid the ZTL higher up the street. Note the accessibility difficulty getting up the long flight of (200) steps from the street. Alternatively there is a small handicap accessible parking lot that avoids the stairs at the end of Via delle Porte Sante. Again, look closely on Google Maps Street view, as access isn't straight forward, and be sure to display the placard. It might be simpler all round to just take a taxi.

Thank you for your responses! If we can squeeze a visit in on an earlier day, we might take a taxi. We do plan to register our license plate for disabled access to the ZTL.

Yes it is possible.
I'm not sure there is handicapped parking at the basilica, I doubt it, but there is plenty of pay parking at the bottom of the staircase below.
You will need to go up the staircase however, in case you have mobility issues.
The way to go up closer to the church and avoid the stairs is to drive up via delle Porte Sante to the end on the north side of the complex (here). There is an entrance there, more or less where there is the pharmacy. You may not be able to park there, but at least a person with disability can be dropped off. That's the only way to avoid the staircase from the pay lot.

Below is the staircase from where you park.
https://maps.app.goo.gl/biV5zRzSpVVPty4F7

But if you drive up to the end of Via delle Porte Sante you end up here:
https://maps.app.goo.gl/ex1MUXJUD7Uy2GSz6

I usually park here (for free), but only if there are no cars (like in winter).

Then you walk through that arch.

Now look a the image below. You will come from that arch where you see those people walking away in the image below (the glass door on the left is the monks' pharmacy). So you are basically in front of the church and by doing so you avoid the staircase in the first image above. No guarantee you will be able to park up there, and in high season I don't know if you find parking, but at least a disabled person can be dropped off.
https://maps.app.goo.gl/QzN22fXvpm2dBTGBA