Ok, two things comes to mind, not specifically with SU but softwares in general :
- try launching sketchup by doing a right click on it then open. this bypasses the basic security against unknown softwares.
- in mac os’s preferences, look for confidentiality/security, and scroll down. check if your mac is set to accept any app from the store, or trusted devs too.
-have you tried the steps Alyce listed ? SketchUp 2025 Won't Open and Hangs - #7 by UniquelyCreated
@colin and @Barry , our resident experts, are likely asleep right now, being in the us and all. but I’ve pinged them.