Convert iPhoto library to photos in Ventura or is it too late

You could never import a library. You could migrate one. If you already had a Photos library, migration would eave you with two distinct Photos libraries. With the current version (v8) you can import from an iPhoto library to a Photos one.

You cannot convert your library, but you can import the images with the loss of some information. If you know someone with an older OS, it might work out better.

You used to be able to import a library from the past. Try going to Monterey or lower if possible to see if it'll let you do so there. Apple Photos usually gets updated with major updates

Ah, seems I used the wrong terminology. MB