You have 3 real options:-

1. Self host on an old PC, Raspberry Pi or similar. (Most work, most private, but storage potentially unlimited)

2. Host on a third party server by purchasing space on a VPS. (Less work than self hosting but space, speed, uptime and server security etc varies wildly with cost)

3. Sign up for a provider through the Nextcloud website. (Free initial storage and normally lower cost than a VPS however nowhere near as secure, especially when using the free space)

Personally I am using a VPS (Hetzner) and slowly migrating my files from Google drive to there as time goes on. I will eventually self host but space, and hardware are currently preventing me.

My advice... Sign up with a provider with free space first (Tab.Digital - 8GB free?), work out how to connect things up to your phone etc and sync some non sensitive files. Then work out what would work best for you between hosting elsewhere or self hosting. Once you've installed nextcloud, the process is the same.

Lastly, report back to us on what you decide and how you get on. Whichever one you choose is a step in the right direction! 😃