As for the secure use outside your home, see if you can install TailScale on that NAS. I use it on mine, it’s like having a Wireguard VPN but you don’t have to mess with port forwarding. The only downside is that to connect to your NAS from outside your LAN, you’ll have to be on a device that’s also running TailScale, but if it’s a device you own that’s easy to set up.
As for the secure use outside your home, see if you can install TailScale on that NAS. I use it on mine, it’s like having a Wireguard VPN but you don’t have to mess with port forwarding. The only downside is that to connect to your NAS from outside your LAN, you’ll have to be on a device that’s also running TailScale, but if it’s a device you own that’s easy to set up.