connection at CDG to get to Italy

1 1/2 hours is very tight, I wouldn’t chance it.
Frankfurt or Munich would be easier. Frankfurt would be my first choice, we’ve never had a problem there.

United flies from SFO to Milan with your only change in Newark. You might consider that route. It’s just a 2 hour fast train plus one hour to get from MXP to Milano Centrale

I've done SFO to FLR many times via all the possible combinations, which, for Florence are:
SFO>CDG>FLR (with AirFrance)
SFO>ZRH>FLR (with SwissAir)
SFO>MUC>FLR (with Lufthansa/AirDolomiti)
SFO>FRA>FLR (with Lufthansa)
My wife has also done via AMS with KLM (I've done via KLM only to Linate).
The easiest is via Munich (MUC), because of the extraordinary ease of making connections at MUC.
FRA is also good in recent years once they organized the non Schengen flights from the upper floor of the same terminal as the Schengen flights (previously it was the longest walk ever).
CDG is the hugest airport. Looks like SFO, only much bigger. 1.5 hours is very tight, but you can take a chance. I've made the transfer in that time, and only once I missed the connection to FLR. No big deal. AirFrance booked me for the next flight to FLR and gave us restaurant coupons to use during the wait. The SFO-CDG flight arrives in the late morning, but there are 5 or 6 flights a day to FLR, the last one of which departs at 8:20pm, so there are plenty of opportunities in case your flight arrives too late for you to make your intended short connection. If the price is right, I see no reason for not chancing it. As I said, the worst that can happen is to be rebooked for the next flight to Florence, and Air France has the most flights to Florence.
If prices are similar, then my preference goes to Lufthansa. Munich is the best connection, the only problem is that the SFO-MUC is the latest flight from SFO to Germany, and that means it gets there later, and there are only 3 flights a day to Florence, so if you happen to miss the connection, it's a long wait till the 3rd and last flight to Florence in the evening. Frankfurt is also a good option, with 4 or 5 flights to Florence. All the German flights to FLR are now operated by Air Dolomiti, a subsidiary of Lufthansa, aboard a regional jet Embraer 190. AirFrance uses the Airbus A318.

We connected at CDG to get to Milan last August. I timed how long it took us to get to the gate of our plane from the time we deplaned. It took us 2 hours and we did not dilly dally. There were two security lines we had to go through which slowed us down. We had carry on luggage only.

I have only once been through Frankfort and did not find it much better.

Thanks for all of the thoughtful replies, really appreciate you all and this forum!

Florence has a pretty small airport, you might find more options if you look for flights to Pisa.

Although Florence has a smaller airport than Pisa, however the nearly totality of flights out of Pisa are low cost airlines (e.g. RyanAir, WizzAir, Easyjet). Pisa has even fewer options than Florence with traditional airlines (e.g. Air France, KLM, Lufthansa/AirDolomiti, Swiss). In alternative to Florence you may look into Bologna instead (which is just as far as Pisa), and of course, Rome FCO. As I mentioned earlier, flying through CDG with only 90 min between flights is tight, but it is not impossible, and if you miss the flight, AirFrance simply puts you on the next flight to Florence.