I too bought the LG Oled 65 and switched to DTV at the same time. Can't help you out on what equipment to get. I was told the setup included the latest gear. Personally, I thing DTV's 4K service sucks unless you want to watch 4K rental movies. AFAIK, the only other DTV 4K channel is 106 with spotty service. I almost never watch it. LG's apps (NetFlix, Amazon Prime and youtube) provide a lot of 4K service via streaming. I'm getting that service via ethernet from my provider and to my tired 79 year eyes, it generally looks great. I also added the Apple 4K ATV which also has a lot of 4K options, again steamed.
IMHO, the picture on the LG Oled looks great on almost every channel. I'm told it converts HD to near 4K video. Don't know if that true, but it looks good to me.
I'm paying somewhere around $11 for 4K service on NetFlix and the standard Amazon Prime $99 annual fee.
I read that DTV is putting up new birds with greater bandwidth ability in the near future so maybe we'll see more 4K service from their satellites soon. One of the most annoying things about DTV's 4K service on channel 106 is the "pop" like it's changing gears to 4K mode.