Fitz Roy or Torres del Paine?

Yes I have been to Patagonia and adjacent Tierra del Fuego, but I'm not sure South America will be a better destination than Europe, Chile is on the verge of locking down the country too. Considering you are coming from the USA, now a Covid-19 hotspot, I doubt they will even approve your Visa.

Any advice/suggestions?

Yes. Stay home. Honestly, it's extremely unlikely that you are going to be getting on a plane to anywhere, for a long time.
How long? Probably for the rest of this year. Might be a bit less, maybe a lot longer. Accept it, deal with it.

Not planning to fly tomorrow. Looking ahead to later this year.

I haven't been to Fitz Roy. But Torres del Paine is one of the most beautiful places I've ever been in the world.

We just got back from that region last week. The area is unbelievably gorgeous. Depending on your time, you could do both. We did the w-trek in Torres del Paine, which took 5 days, and then we spent 3 nights in El Chalten and hiked around Fitz Roy from there. We had never taken a trip like that, so we took a hiking tour with Active Adventures. Their Condor trip has a great itinerary that I think would be reasonably easy to follow on your own, if you didn't want to go with a group. Whatever you decide, it will be a great adventure!

We did both, two years ago, in March. Our trip was similar to Tamara's but we went with MT Sobek, a long-established adventure tour company based in Berkeley. The guides and driver were local and were excellent.

The Torres Del Paine viewpoint is a dayhikes usually done as part of the "W" trek, so -named as that is the shape. We did that over three days, with overnights in Refugio's at the beginning, middle, and end. Then we hiked to Lago Grey and rode a boat to a hotel on the lake. From there our van took us into Argentina.

For Fitz Roy,we stayed in a beautiful rubric Lodge outside the town of El Chatén, named Refugio Laguna Condores. I highly recommend it.

https://lagunacondor.com/en/home-2/

We hiked both sides of Fitz Roy on successive days. Personally I found this hiking even more scenic than the Torres Del Paine. But my favorite mountains of the trip were Los Cuernos, which we had in view for two days on the W trek.

Maybe next February or March . . . .

Thanks for the feedback and recommendations! Going to give it a hard look once things start getting back to normal.