Thank you for giving the request a shot. It's nice to know at least it's partially possible and might be in the future (maybe?). Also I'm too much of a stickler for accuracy and wouldn't really mind MW2022's version if and when it's fully available. Since it sounds like it's the least problematic right now at least compared to a paywall and some rigging jank. At the very least it'd be nice to play with the Cronen Squall in a mildly less grating game than Warzone 2. Thanks again for the time.

That's not to say the MW2022 model (or Akinaro's) would be free of the same posing problems as the BF2042 version.
The general profile of the RM277 doesnt really match any of the hold or reload animations of the vanilla Payday weapons and would require an animation commission to solve.

The closest match I've found was the KS12 Urban/ASh12 animations on the BF2042 model, but the charging handle would reciprocate when it shouldnt. Attempting to disable the charging handle recoil animations on the charging handle strangely disabled the reload animation too. I am fairly certain the Queen's Wrath/L85 would run into similar issues as the ASh12 animations.

UAR/AUG is out of the question because of the charging handle not matching up to the placement of the charging handle on the RM277. I am fairly certain the Union/F2000 would run into similar issues of charging handle placement.

If you use the Lion's Roar/VHS, the reload animation would possibly match (assuming you're not looking too closely at the charging handle), but the hold animation would result in a floating gun (partially textured is the RM277, untextured is VHS).

The Tempest/X95 and Clarion/FAMAS has similar issues to the VHS in terms of floating hold animation, not to mention the problem of the reciprocating charging handle.

As a silly idea, I even tried the C Clamp grip from my April Fools M4 URGI (I recall the True Velocity video had someone C Clamping the RM277), but checking the pose would result in the player's thumbs clipping through the upper receiver of the RM277. Reload animation is obviously not going to work because of the bullpup nature versus the original animation being intended for AR15s.

So end result is that you'd pretty much need PlayBONK or splish or some other animator to make correct animations somewhere.
splish is busy with his professional animation job and BONK has at least 3 commission requests I know of waiting in a queue (if not more). 
One of those commissions in particular is going to take a large amount of his time, so idk if/when PlayBONK would be able to get around to the RM277, assuming you sent him money.