How to make sure my iPad and iPhone share photos again?

Recently, my 4 year-old, 7th gen iPad was badly damaged. The screen is crack all over and I can no longer interact with it as it's completely black with a few lines of light. I bought a 10th gen, 10.9 inch iPad to replace it, but unfortunately I had the iCloud Backup on my 7th gen disabled because it took up a lot of storage. So outside of signing into my iCloud again, I pretty much had to start anew with the 10th gen.

My iPhone 11 was linked and shared the same photos with on my old 7th gen. Whatever photos I saved/deleted on my phone would save/delete on my iPad and vice versa. How do I get that to happen again between my 10th gen and phone? Is it possible without the iCloud Backup?

Right now, the photos library on my 10th gen says "Syncing with iCloud..." and it hasn't changed. My phone/iCloud has 411 photos and 12 videos. Is it supposed to take a while to transfer or could the size be affecting its load time?

Any advice will be greatly appreciated and thanks for reading.