Once again, thanks for all the feedback. It helps a lot to talk this out with people that are knowledgeable. Brief overview of workflow. Shooting in RAW on Nikon camera (in camera color space Adobe RGB) =>
First off, that plays zero role on the raw data. It's only a setting that affects the camera processed JPEG. Yes, it affects the Histogram on the camera but that's not a raw Histogram so it's a lie about that data no matter what you set.
Yes, you're rendering from raw to ProPhoto RGB; that's good. We can go into why if you wish. But stick to that plan.
Now you save a JPEG that you've converted to sRGB and to a size necessary to post to the web. That too is all good.
That they don't match Photoshop or Lightroom is the issue with your browser! And saving as sRGB as indicated in the video isn't an insurance of proper color previewing UNLESS the browser is color managed. Yes, sRGB is the best solution for viewing data on an sRGB like display without color management. But the opposite is true on a wide gamut display again as outlined in the video. If you view sRGB on a wide gamut display without color management, it looks wrong. If you view Adobe RGB (1998) on the same display, it looks 'better' but again, without color management, there is zero guarantee it will match what you saw correctly in LR which is color managed.
So your issue is the browser I believe based on what you're telling me (and no, setting the display to sRGB as incorrectly suggested is throwing the baby out with the bath water and doesn't really fix anything. It goes to the sad fact that, the reason there's so much ignorance on the subject of color management, is that those who have it are so eager to regularly share it!).
Chrome is not a color managed browser; dump it.
https://cameratico.com/guides/web-browser-color-management-guide/