If you need to get reviews of performance plans or if you need to collaborate on initial drafts of performance plans, you have a couple of options:
If you're using a budget bid strategy: In a serial fashion, ask each person who needs to give input to look at the plan in the Search Ads 360 interface. As there is no way to lock the state of a plan, anyone with sufficient permission can modify it. If you're sharing a plan with other team members whose permissions let them make changes, keep a record of changes so that you're able to revert to a known state if necessary.
If you're managing the plan manually: You have the option with manually managed plans to download a spreadsheet of the plan configuration. In this case, you can share the spreadsheet, gather input until you've arrived at a final state and then upload the finished spreadsheet that contains the final version of the plan.