Extracting Histogram Information on a large scale

I'll 2nd the suggestion for using RawDigger if you want the actual data of the raw, not rendered, Histogram data, in a defined color space with dog knows how many edits applied in the raw processor. 

But until you tell us what data you want or need, impossible to go further. 

Do you just want the picture of the histogram, or the actual data? For raw photos, or rendered?

If you just want the picture of the histogram for each raw photo, it’s possible to import a lot of photos into Lightroom Classic, then use a separate macro program to record the following sequence:

1. Take a screen shot of the Histogram panel and save it to storage. 

2. Press the right arrow key to advance one photo. 

3. Repeat steps 1 and 2 until all photos are done.

Just think carefully about what kind of histogram you want, because if you simply import raw photos without changing anything, the histograms will represent this:

• The default rendering for raw photos, with the default Adobe import settings (raw profile, preset, etc.).
• ProPhoto RGB color space with sRGB tonal response curve.

That means the histogram you get may not match the histogram you get from the camera or other software, because they all have different default rendering settings. If you have specific requirements for your histogram, you’ll want to switch into the Develop module, enable Soft Proofing, specify the ICC color profile and other settings for how you want the histogram to be defined, and then take the screen shots of the Develop histogram.

If you want the data, not the picture, you might want to try RawDigger (commercial software), shown in the pictures below. It has a Save Full Data button for its histogram. For a batch of photos, you would have to find a way to automate that. If all of your photos are in one folder, your automation can use the RawDigger command File > Next File or its keyboard shortcut.

RawDigger exports in .csv so you can open and analyze your histogram data in a spreadsheet editor:

But again, before you begin, you’ll want to go into the Histogram preferences in RawDigger and make sure its histogram is set to the data range and color rendering you actually want.

What on earth would you expect to do with that?

That makes little sense. Please expand upon that. The histogram is an interpretation of data. Not a file, not metadata.