On my website, I have my photos grouped in various categories (Faces, Landscapes, Animals. etc.).
In Lightroom Classic, I have a Keyword structure setup to mirror those categories.
I also created Collections with the same names.
I use the Keyword panel to focus on the photos in a specific group (e.g., Faces). Those photos that I feel are deserving a place on my website, I add to the corresponding Collection.
If you have applied Keywords to all of your photos in Lightroom Classic, you might employ a similar approach.
If you haven't done any keywording in Lightroom Classic & don't wish to do so, you might have another way in mind to tackle this task, but I still would suggest you utilize Lightroom Collections to gather photos for your website.
This way you will have a quick reference should you wish to add or delete photos from your website in the future.