How much would it cost to repair my MacBook Pro M3 Pro

Around $100 USD if you have Apple Care+ for it. Much much more, if you don't have Apple Care+.

See the following link to get an estimate.

click here ➜ Mac Repair & Service - Apple Support

We are not Apple but other end users like you, so cannot estimate exact costs unseen except from our experiences and reports others post here. Also, these are international English-language forums, and service costs vary wildly from country to country.

From reports here, any damage to a Macbook Pro display—a sealed unit— requires a complete new display assembly. Individual display parts cannot be separately replaced. Depending on device age and screen size, reports here by U.S. users needing out-of-warranty display repairs run between US$500 and $700.