If you just want to use a VPN to access your network share from outside your home, I recommend Tailscale. It's a great way to extend your home network. LTT has mentioned it a few times in their videos.
You install the tailscale client on other devices, then map the drive like it's a local NAS.
If that is not an option, then like @Electronics Wizardy mentioned, Nextcloud is an option. You need to be familiar with basic home-hosting to do something like this (have your own domain, point it to your public IP, open port on your router) and Nextcloud's server will require Docker or a virtual machine if you're using Windows.
If you want something cross-platform (installs natively on Windows) to sync files, you can also use syncthing. It simplifies some of the home-hosting stuff. It's got a ton of options but can be overwhelming. It can be as a web app or a desktop app as well.
Nextcloud was my gateway to the world of home-hosting. It's a great piece of software.