Seamless Time Machine Wi-Fi backups now that Time Capsule is discontinued?
Yes, some NAS work as seamlessly as the Time Capsule. For example Synology DSM has great Time Machine support. There's no need need to manually mount/unmount the network share for each backup.

You can read Apple's list of other options here:

https://support.apple.com/en-us/HT202784

It is essentially either a local drive connected to your Mac (via USB, Thunderbolt, Firewire, SATA, whatever) or a network volume using AFP (NAS, PC/Mac, Time Capsule or AirPort Extreme with external drive connected).