I've been working with a MS engineer on building out Flows rather that SP2013 Workflows for my environment. He suggested going with a script-like method rather than Do...Until loops to avoid the 30 day Flow timeout and not require a PA Premium license.
The plan is to run a kickstart Flow that will read current state and create the List/DB entries for all existing projects at their current stage, then add an Enterprise Custom Field for "Submit to workflow" on the PDP that will kick off the script on publish.
While I like having the features of Power Automate at my disposal, losing the user experience of the Workflow ribbon buttons in PWA/Project Online is going to be a rough transition for my userbase: it's taken years to get them using those buttons in the first place. I really wish this transition had been baked a bit longer before being pushed.