Nextcloud running directly on a Linux phone would be the ultimate personal privacy cloud. Your data would never hit the Internet, and it could sync to your laptop and other computers over the hotspot connection, once again, never going over the Internet.
I used the PinePhone original as my daily driver until it died, for about 8 months. It was painful, but doable. Worst part was battery life, and I used a Bluetooth earpiece because the earpiece was joke.