The wired connections usually needs just a DHCP server to obtain address/netmask/gateway so if em0 interface properly configured in /etc/rc.conf — it will get all necessary configuration automatically.
The wireless served by wpa_supplicant, so if you connected to the desired network and has necessary keys in the /etc/wpa_supplicant.conf — the machine will connect to the WiFi network by itself. If it is a new network — well, the new lines could be added to that file via CLI with the help of wpa_passphrase, or via GUI with the help of wifimgr program (which is basically an interface for wpa_cli program).
The switching between wired/wireless interfaces could be performed by kernel — just create aggregate interface (lagg0), add em0 and wlan0 interfaces to it and the system will switch between em0 and wlan0 automatically.
Before, I was searching for "NetworkManager for FreeBSD" too, but all corresponding projects were long-time dead and after re-reading the FreeBSD Handbook I found that it is not necessary and just adding an unwanted layer of complexity, comparing with aggregate network interface.
In worst case scenario (hardware manufacturer unable to provide the necessary bits, so WiFi interface could not be added to the aggregated network interface) — the automation via devd events could help, like described here: https://codeberg.org/evgandr/dotfiles/src/branch/master/noauto/etc/devd/dhclient.conf and https://codeberg.org/evgandr/dotfiles/src/branch/master/noauto/root/bin/unfuck_network.sh
As you can see, the same files help in 3rd case — when I want to connect laptop to the Internet via USB-tethered phone and ue0 interface. The interface itself is configured literally with 3 lines in /etc/rc.conf: https://eugene-andrienko.com/2025-03-10-freebsd14-2-thinkpad-x220.html#usb-tethering
#FreeBSD
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