iPhone pictures Backup

Unfortunately my iPhone hasn’t been on wifi overnight since 2/22/2022. And it hasn’t been backed up since then. Now I want to transfer my phone contents to a new phone and have been unable to successfully back up to iCloud. We tried at the Verizon store and after 6 hours gave up and then overnight on a wifi/power source it still had 12 hours it said in the morning. Is there anything else I could do to backup my pictures?