Sure this has nothing på do with libreelec on S905/S905X - you should learn to google and read.
I gathered you currently have a DVB-T USB dongle working perfectly with your TV Box to accept local free-to-air (FTA) US TV channels here in the US? If so, I sure would like to know which city and/or state you are in. The reason I asked this is because I know a DVB-T is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television used in EU countries while ATSC standard is largely a replacement for the analog NTSC standard and it is a set of standards for digital television transmission over terrestrial, cable, and satellite networks used mostly in the North America, i.e. Canada. Mexico, and United States. To support what I said, please see this DVB-T USB dongle digital television sticks do NOT function in the United States, Canada, nor Mexico video (circa 2012) and/or this post (circa 2016). If you and/or anyone here can confirm a DVB-T, especially a DVB-T2, USB dongle that works with a TV Box running on an LE 8.1.x to accept FTA US TV channels, then I would like to get one of the DVB-T2 USB dongle to work with my S905 TV Box running on an LE 8.1.x to watch local FTA TV channels.