I have a decent sized antenna in my attic which is connected to a HDHomeRun Flex Duo, allows for two simultaneous channel streams at once. From there, this sits on my network and on my Apple TVs, iPhones, iPads, Mac and Windows PC... they all use the HDHomeRun app and I have all of the channels and a guide. Watched in on the 55" TV in our living room via that app broadcasted by the local CBS affiliate, WIVB-TV in Buffalo, Channel 4.
The Mac app, while it is supposed to support Mac OS X High Sierra (yeah holy old!), it only crashed on my antique iMac in my shed. Fortunately though, the HDHomeRun Flex Duo is nothing more than usual network streams and I'm able to open them via VLC. So I can still watch OTA in the shed with the old cold ancient iMac.