There are
lots of examples on this site selling an instrument for measuring chamber pressure. There are examples in this
1965 study of pressures that have more discussion.
The faster a powder burns, the faster the initial spike's rise for a given cartridge and bullet weight. If the average pressure during the bullet's whole trip down the barrel is the same for two different powders, then the projectile's kinetic energy and, therefore, the final velocity will be the same for both. In that instance, the faster powder produces a higher, faster spike, but does it with less total gas (the bullet is not as far down the barrel), so the muzzle pressure is lower. In comparison, the slower powder will use a higher total energy charge to produce more gas with a lower, slightly slower rising peak but also produces higher muzzle pressure to wind up at the same average.
Both examples could be a more accurate load. It depends on several factors. One is the barrel time. Even though the velocities in that example match, the faster powder will produce a shorter barrel time because it reaches its peak sooner, which is where bullet acceleration is at its maximum, so the bullet starts out faster down the barrel, shortening the time it takes to reach the muzzle. If the gun's barrel vibration sweet spot is better synchronized with a longer barrel time, it will like slower powder better and vice versa. Slower powder with its more gradual pressure slope and higher muzzle pressure and greater charge weight will produce more recoil because it ejects a larger quantity of gas at higher pressure. That's called the rocket effect and it can be responsible for over half the total recoil in some overbore cartridges (it is what a muzzle brake mitigates by venting gas sideways). The higher muzzle pressure means the muscle blast venting against the bullet base as it exits will contribute more to the bullet's initial yaw. This causes it to take a longer time for the bullet to "go to sleep" and has been measured to increase flight time by reducing the effective ballistic coefficient during the settling period.
Lots of tradeoffs and no simple answer, alas.