An old series of posts which highlights quite well why GitFlow can be a problem and that you likely want something simpler. Since I still find GitFlow often recommended as a knee-jerk reaction, this is a good article to have in hand.

Nice list of templates to use for better handling of engineering management in your organisation. Pick, choose and adapt what makes sense to the context.

There are indeed way to deal with important but lower priority tasks. You want to tackle those to avoid your teams to slow down too dramatically.

Maybe it's time to stop obsessing about scale and distributed architectures? The hardware has been improved quite a bit at the right places, especially storage.