Hi @deny21
You can do the bulk product edit and set its visibility to only catalog.
1. If all lessons are in the same parent category you can go to Products -> Categories and click on the number on the right side of the all lessons category, see example: https://prnt.sc/V4b-SCgUGKlc.
2. This will redirect you to the product list that belongs to this one category. Now you can bulk edit it by selecting all products like here: https://prnt.sc/MVAWt3piCwgs and click edit.
3. Now you should see the bulk edit options so you can set visibility of all these products to Catalog only like on the screenshot: https://prnt.sc/mHyZYJBkAgL9 then update.
P.S. If you have more than 1 page in the product list, you can expand the Screen Options and increase the number of items per page options like here: https://prnt.sc/UybLYqWkH1u6 to speed up the process.
Regards,
Kris