U.S. Capital Gains and Foreign Tax Credit

Hello, I’m hoping there is an American on the SF website who has had to declare US sourced capital gains (from the sale of shares) in France
I have a hard time deciphering the US-France Tax Treaty, as well as the IRS information on the sale of US shares and the Foreign Tax Credit.

We may become French residents next year (depending on the pandemic situation) and I am trying to figure out if I should sell our shares this year, before that happens.
We don’t pay any tax in the US on the gains from the sale of shares, but I know we would have to declare those gains as French residents.

What I don’t know is, will we have to pay tax on those capital gains in France?
And if they do, would we be able to claim that as foreign tax credit, even though we wouldn’t have paid any tax on those gains in the US?

We don’t expect to have any French sourced income, except for maybe some bank interest, and my wife’s French pension, which she will begin collecting four years from now.
I’ve searched and searched online but I can’t seem to find the answers to those questions (or maybe I have and didn’t know it!).

There must be someone on the SF website who has dealt with this issue.
Any help would be greatly appreciated!