Google Ads has introduced channel prioritization and budget caps for various campaign types, including Performance Max, Shopping, and Search campaigns. This update is currently live (also spotted outside of the US), allowing advertisers to control budget allocations across different channels.
This feature lets users allocate budgets either as high or low priority, ensuring high-priority channels are funded before others. Read more about it here.

Google shared that it plans to make this available for Demand Gen campaigns in the future as well.
This update was shared by Thomas Eccel.