Photos do not have to all be downloaded to the device. It will manage the storage and mainly keep more recent photos on device. It will download others as neede

Photos do not have to all be downloaded to the device. It will manage the storage and mainly keep more recent photos on device. It will download others as needed. That may not be perfect for you but it does help offset the storage situation. I have an iPad Prod with 256GB of storage and it is currently only using 70GB.