for some reason that is not universally true. Several folks say that they can see it as an ESPN channel choice with ESPNWatch/ESPN3, but others (such as me) do not see it... so it is likely market/provider driven situation.
there was an earlier question in the pinned post about Youtube TV that was not yet answered. I know that youtube TV have a free-weekly trail, but I think available channels are based on your internet zip code, so not sure if PAC12 is “standard” available channel.. hopefully a YouTube tv user will see this and answer for the earlier poster.
as to the OP of this thread, if your current subscription does not carry PAC12, and you are unwilling or unable to subscribe to it, your video streaming option Might be on Fubo TV which others in the pinned thread above said includes the PAC12 network and also offers a free-weekly trail. (And possibly the response to the YouTube tv question). But I am unfamiliar with FuboTV and channels availability.
if all else is lost... It is confirmed to be radio broadcast on WRSC 1390AM & and audio streamed on GoPSU