iPhoto app on iMac wont open... keeps crashing right after it opens

Photos crashes on me from time to time but, really, not often. You're running Ventura-- do you have any crazy non-Apple apps for cleaning and such?

Most important, you did not tell us where your Photos Library is located. Is it in the Pictures folder, or is it on an external drive? If it's on an external drive, how is this drive formatted? To avoid damaging the Photos Library an external drive must be formatted in either APFS format or Mac OS Extended (Journaled) format. Additionally, the drive can not have had Time Machine on it since it was formatted. There have been so many problems with using incompatible drives that the newest macOSs won't even allow a Library on a non-Mac formatted drive to open, since there is a chance of damaging the Photos database. See this:

Move your Photos library to save space on your Mac - Apple Support

If this drive is in a an incompatible format, stop running Photos with it immediately!  A Photos Library can sit on an incompatible drive, but running it may corrupt the database.

Do you use iCloud Photos to synchronize your Photos Libraries? If so, do you use "Optimize Storage?"

If your drive is OK, then to narrow things down, try these steps:

• Restart the computer (of course)
• Re-start in Safe Mode. This bypasses certain potentially disruptive processes, and it often helps. Safe Mode is different for different computers, so see this: 

           Start up your Mac in safe mode - Apple Support 

• Use another library if you have one, or make a small test Library with a few pictures in it and see if the same thing happens. You can create a new Library by closing Photos and then option-clicking on the Photos icon.
• Make a new user and see if the same problem recurs with it
• Rebuilding your Photos Library was a good step.

The idea is to find out if the problem is with the Library, with your account, or with caches and login items, and stuff like that. One of these steps may fix the problem, but their failure to work also helps figure out what's happening.

Let us know what happens…

Have you tried starting it with the option key held down to create a new library?

Create additional photo libraries in Photos on Mac - Apple Support

You can also try Safe Mode:

Start up your Mac in safe mode - Apple Support

I have the same issue! Really, I start the app, and absolutely nothing happens I till I force shutdown an hour later.

My library is in the Pictures folder (Swedish OS, so guessing it's called Pictures), I'm running MacOS Sequoia on a Macbook Air that still has warranty on it.

And yes, I tried opening the app and creating a new, empty library. I open the app while pressing the Options key, and nothing happens. I tried for the fourth time this morning, after 2 hours I got the option to create a new library. I took that option, it took 1 more hour before the app opened with the empty library. I imported my original library and the app promptly seized up

The photo library is 42GB in size and I want to import and consolidate some small older libraries