Does OpenWrt make any outside connections by itself?

Not a fan of data collection or telemetry of any sort, including pings to random places to determine whether I am online or not. Does version 21.02 make any outside connections by default? If so, how can it be disabled entirely?

OpenWrt does not phone home or do any telemetry on its own with a default installation of an official OpenWrt build. The router shouldn't be generating any traffic of its own aside from NTP syncs (which you could theoretically disable) and upstream DHCP or PPPoE connection related stuff (if applicable, and necessary if you have those types of connections).

If you install other packages, obviously it depends on what they are for -- so for example, a DDNS client will need to send IP information to the DDNS registrar of choice.