Tongue-and-groove flooring jack - GIF

[metric_taper]

As much as that wall appears to move I suspect base board and drywall should have been removed to inspect the sill plate before worrying about a floating wood floor

(edit, I needed to play the video)

I have one of these, and it's for tongue and groove flooring. Also, I have to put a 2x4 or other structural lumber up against the wall to spread the load this jack imparts. It's high enough to crush the sheet rock. And will rotate over the bottom plate that the sheet rock is attached to, which for the 3/4" flooring is 3/4" above the finished floor. And you can see the part that has the ratchet pawl mechanism sits above the face of the flooring about 3/8" so it tends to want to push up with jacking force. If that makes sense. Anyway, you can damage the wall real quick with one of these. I've used them far away from the wall with blocks to space out from the wall, as well screwing down a 2x4 next to the piece I'm installing to jack against. And I've used angle iron steel when I needed to be close into the wall. Problem with some warped pieces need to be coaxed into place. But 2-1/4" is not too bad, but last floor was 5", and oak does not want to bend very well with that width.
It's a handy tool for what it does. Mainly next to the wall getting the joints tight.
A side photo of the tool; Note how long that angle part that sits over the edge of the flooring is.