My biggest take-away (and it's served me well as a team lead) is minimize work in progress (WIP). In practice, that meant encouraging contributors to focus on getting opened PRs reviewed/merged/deployed rather than opening new ones - which has cascading benefits.
A related takeaway is that when resources (engineers, key machines) are planned to be at capacity, they have no slack for dealing with unplanned work, so it's good to plan for resources to be under-utilized at certain times so that they can be more agile.
I've never seen "The Profit" but I'm looking forward to watching it now!
 - https://www.amazon.com/Phoenix-Project-DevOps-Helping-Busine...
EDIT: for link to book