Can a M4 Pro mini enhance video editing performance on a 2019 MacBook Pro 13" with 8GB RAM?

A Mac mini is a complete computer in and of itself.

It does not add to or supplement for an existing computer. You can't plug into your MacBook Pro and increase its performance.

It's like asking if a new MacBook Pro would enhance video editing performance on your old MacBook Pro.

It doesn't work that way. It's not an add-on.

Yes, you can buy a Mac mini and run DaVinci Resolve on it and will work leagues better tan your current MacBook Pro. But will be entirely independent of it.

You would need a monitor, keyboard and mouse for the Mac mini though.

[in my opinion] 8GB of real RAM is not enough to run Ventura or later in an appropriately responsive way. Apple no longer sells ANY Apple-silicon Mac with only 8GB or real RAM, because that is simply not enough.

If you want to keep using Apps like Video editing, you will have to change the way you work, and rather dramatically. You will need to QUIT each App before you open the next, and plan on restarting often, multiple times throughout the day.

Or obtain a computer that better meets your needs.

RE: using a Mac mini M4:

A Mac mini M4 can run rings around your MacBook Pro. Its best use for Video Editing would be to completely REPLACE your hopelessly hobbled MacBook Pro with only 8GB RAM.

But for that matter, ANY Apple-silicon Mac with more than 8GB RAM could do that job better than your current Intel Mac.