If Obsidian keeps crashing on startup, it might be difficult to copy the debug info. “30-40” plugins does seem a lot for mobile.
@Stof What do you use to sync? iCloud or Obsidian Sync?
Do you have any iOS apps that can edit hidden files/folders? Textastic (paid) and Taio (free) both work fine and are easier than the command line ones. See: https://forum.obsidian.md/t/mobile-ios-app-to-work-with-hidden-folder/25741
If you’re confident it’s the Graph causing the issue, you could try to reset the graph settings. The file to move or rename is MYVAULT/.obsidian/graph.json
If you use iCloud you can move/rename this file from the Mac in the iCloud directory. If you use Obsidian Sync (depending on your sync settings) you may have to edit the file directly on iOS/iPadOS using one of the above apps.
NOTE: this will reset any custom graph settings on both desktop and mobile (depending on your sync setup). It’s worth a shot.