I recommend using syncthing. It's very easy to self host but I actually use a SaaS for it: syncding.com. It gets me 100gb to 1tb of disk in which I can create folders and keep them synced with my 2 laptops, my phone, my server etc... I have an Obsidian vault with Meld Encrypt to encrypt some files, a keepassxc file I share across my devices and my todo.txt

It's simple to setup and will work forever instead of paying for different providers that might shut down or increase their prices.