Having read 350 of the 511 posts on that thread, my understanding is:
1) Resolve 16 began adding metadata tags for gamma to its exports.
2) Each video player (VLC, Vimeo, YT, QTX, QT7, and OS versions) responds differently to metadata tags and has different gamma defaults. This is why you see the same file with different gamma on the same screen.
3) DCP and broadcast also have gamma standards.
4) The best is an I/O device, calibrated display, and color management. Make an accurate grade on the calibrated display, then export the correct color-managed gamma for each deliverable.
5) A calibrated display reduces half of the possible variations between grade and delivery. Beyond that you will never solve infinite screens and infinite players. Give up and stay sane. No one will ever see your grade as it is in the color suite.
6) If you don't have a calibrated display and use a "close enough" computer monitor, you have exponentially more variables. Since YT, Vimeo, QTX all treat tags differently and your OS has gamma settings too, the Resolve GUI will not match all players and you don't really know what is happening. You can change the timeline gamma settings to match your delivery color space, or put a conversion LUT on a timeline node to get the Resolve GUI to look closer to your delivery player, but all of this is wonky and breaks things in other places. YMMV.
7) Use color bars. Use scopes.
This is a good article:
https://blog.frame.io/2019/10/14/gradin ... -delivery/Please correct my errors. I have not yet seen a summary like this. Perhaps this thread can be shorter than the first and useful for linking.