How to recover photos from a lost iPhone with no iCloud backup

If it was not “backed-up“ (or “sync’d”); without the physical device any onboard data is unrecoverable.

However, an iPhone’s default settings turns “on” iCloud Photos … so they MAY be sync’d on your iCloud (albeit w/o your knowledge) …

… unless you explicitly turned this feature “off.”

Given your previous statement that they weren’t sync’d to iCloud …

… if they were ddeleted from the device - and not still retained in “Recently Deleted Photos” …

… they are gone forever.