Buy a Minisforum UM350. Install Linux on it. Set up Tailscale on it and all devices you want to have access to its internal services. Set up Nextcloud on it.
There you go, $300 one-time cost, and you have a very powerful private server that can run all your self-hosted stuff. Via Tailscale, it can even expose some services to the public internet, if you feel the desire to do so.
To add to parents great idea, this is 70 bucks more (currently $320 versus $390 for this on Amazon US) and it's an 8 core ryzen and 32gigbs of ram so will handle a lot more:
Not affiliate, just anecdotal, just purchased this for myself this last fall and its fast and cheap and I feel the best current value from mini pc's at sub 400. The ones at 600-1000 cost are just incrementally better from this one's specs so I feel it's the sweet spot at $390. So your server can be much much beefier for not much more.
There you go, $300 one-time cost, and you have a very powerful private server that can run all your self-hosted stuff. Via Tailscale, it can even expose some services to the public internet, if you feel the desire to do so.