Does Google My Activity show what I do in Google Photos?

If you'd rather it didn't keep any of it, you can pause Web & App Activity, or keep it on and set auto-delete to 3, 18 or 36 months. Both are on the Web & App Activity page in your Google account. Pausing affects other Google apps too though, search suggestions get less personal.

Some of it, not everything. It only records anything if Web & App Activity is on, and for Photos it's mostly searches and a few actions rather than a log of every photo you open. Easiest way to see your own is to open My Activity, filter by Google Photos and look at what's actually listed.