It sounds like you might not have other options right now?

I think I would find therapy (and likely any lengthy communication) quite challenging with a masks on. it might be worthwhile, nonetheless?
Maybe bring a supply of large cards with emojis on them, holding up the card/emoji which most closely represents your emotions during the session?
I think I'd feel a b it impaired, as I look for all kinds of cues, I think we all do.

If my therapist had decided to do therapy this way, I'd give it a solid chance.

If you have a say in the distance between you two and the meeting room allows for it, separate for more distance, like 9-10 feet. Studies clearly show it's much safer at 9-10 feet of separation.
If the further distance between you and your therapist creates difficulties hearing one another, maybe ask her to look into a small "white noise" machine/gadget. Many, many therapists use them. They are very small, round units that sit maybe 4" high (or less) and therapists place them outside of their doors.. They make it difficult for people to hear what's being said in therapy. just a thought.

Good luck! I 'll be interested in the outcome.
Take great care. Be well!