How the hell do I grind this sh!t faster lmao

grind

here are my unlocked vehicles:

Now I want to grind USA fast, and how do I do it?

By grinding more vehicles and spading them.
Spading vehicles awards aditional RP, for the M4 T26 it is 8000 bonus RP for spading. menaing fully spading just that tanks gives you ~48600RP for the next vehicle (even more if you are researching the M26 with the M4 T26. Just researching two mods in each line would only give you 22000RP.

Actually spading vehicles will naturally unlock new vehicles. While it does not really shorten the grind it does help mentally. Instead of needing 105k RP for one tank you now go for 4k RP for that mod. So you actually perceive progress as faster.

Outside of the mental factore there is nothing you can do outside of spending money for premium, buying a premium vehicle or putting a talisman on another vehicle. You could also spend real money to convert the “free” RP at an abysmal rate (RP gain to GE cost) and get the vehicle that way.

Then what mode are you playing? AB, RB or Sim? AB is good for farming crew XP but bad for fast progression through aTT. RB has higher rewards, but is also a bit harder to play. Sim is very hard to play (due to teamkilling being thing) but offers the best rewards. Generally I would advise playing RB for the best balance of RP gain and crew XP gain.
No matter what you need to unlock more vehicles at each BR for proper lineups to be more effective in matches. While in one match you may die in one hit in your T32 and gain 90Rp for that match you could also respawn in the M 47 and get 12 kills and 3 caps in that second spawn. So while not progressing your T32 spading run you would still gain aditional RP for the overall grind of the TT from that secondary vehicle. More vehicles also enable you to build a more balanced lineup which is better for winning games. Winning gives aditional RP rewards on top of what you did, also speeding up the grind.