Either "enterprise" WiFi or, if your device supports it, locking down the MAC address. That'll give you range issues if you use mesh wifi, range extenders, or additional access points, though.

I don't know why more devices don't support WPA Enterprise, it's not _that_ complicated a protocol. I can imagine a "secure router" product with a normal WPA3 network for management and an "enterprise" network with a simple username/password list selling quite well in some niche circles.

You can build such a network yourself, though, with almost any OpenWRT device, though it's clearly not something most end users can manage themselves: https://github.com/ouaibe/howto/blob/master/OpenWRT/802.1xOn...