Do WhatsApp photos need to be kept on the device in order to save them?

I have Google Drive backups turned on for WhatsApp, which I understand is for restoring lost conversation history. Android often prompts me to clear out my WhatsApp photos folder, though, to free up space. It makes me anxious because I may accidentally click yes, leaving me with my conversations but no photos.

If I clear the folder, are the photos gone forever?

If not, are they backed up in Google Drive along with the chats? Are they still shown in the app as thumbnails to download from the backup? How does it affect the user experience?

Once cleared, can the photos be accessed in another way? Either through a “preview” of my whole history (unlikely), or a folder in Drive with the photos (still unlikely since it’s probably a hidden, app-specific folder)?