While Microsoft has offered tools to import your Google Ads campaigns into Microsoft Advertising, including PMax import tools - now you can supposedly import from PMax to PMax, with Microsoft fully supporting PMax campaigns these days.
Thomas Eccel told me on X that you can now "import your Pmax and sync your whole Google Merchant Center into your Microsoft Advertising (Bing Ads) Account." When I asked how this is new, he said, "since PMax imports became Search and now with the launch of Bing PMax you can import Pmax to Pmax for the first time."
Here is his fancy (a bit) overly branded screenshot (can't blame him, people just steal stuff and pass it along as their own finds):
So now you can fully import your Google Ads Performance Max campaigns to your Microsoft Advertising Performance Max campaigns.
Forum discussion at X.