You can show all the streaming channels (Roku Live TV channels) as well as the Antenna/OTA channels when you have them enabled in your Settings and select Antenna Input on your RokuTV.
I do not believe you can access your Antenna/OTA channels through the Roku Channel Live TV guide. (At least I cannot and never have been able to on an Insignia RokuTV).
In order to show both Antenna/OTA and Streaming Roku Live TV channels in same guide...
1. Settings/TV Inputs/LiveTV/Manage Channels/Disable (uncheck) Hide All Streaming Channels
2. From Home Screen, Select Antenna Input. (you should now see all OTA and Streaming channels and can further manage/hide/filter them accordingly.
Feel free to post back with an update or if you still need more help.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660x, Premiere+ 3921, Express 4k+ 3941