We’ve just landed support for wifi in the server installer. Obviously most servers don’t have wifi, but this support will be useful for e.g. devices that bridge the gap between AP and server. If you have a device you could test this out on, it would be appreciated!
For now only the ISOs for impish have all the support pieces in place, so please download your ISO from https://cdimage.ubuntu.com/ubuntu-server/daily-live/current/. It should be available on focal ISOs fairly soon.