rusefi.com

Things like https://www.adafruit.com/product/3663 are they relevant for us? Not too cheap. For example could this be used for Frankenso 2x25 everything header? microRusEfi 2x5 ST-Link header?

I lack personal experience. I understand they work well, but are often considered costly. I understand you can't just smash them into your existing via's, you have to hold specific tolerances. As well once you smash it in there, you can not remove and replace with solder. So it's a one time deal. Solder is typically consider flexible and low cost. However in this case, perhaps the increased component costs is better than the chewing up the limited time resources.