I have 50,000 family photos in my LR that I want to share with my extended family only 2 of which own a copy of LR. I particularly want to display my long caption explanations. Is there a widely available free or part of Windows 10 etc. way to do this?
If you write the metadata to xmp using Lightroom Classic, virtually any photographic application, and even your operating system, can read most of the metadata. One such free application is ExifToolGui.
There's also sharing the photos via "the cloud" using Lightroom Classic's feature of sharing the photo in the cloud, and then your family can view the photos on any mobile device or computer. And there are plenty of web-based services such as Flickr (which does charge a fee).