The Internet Archive may not be the first place you look for old-time country sounds, but some old-time radio and 78 rpm record collectors have digitized an amazing amount of 20th century American culture.
I'll come back and edit this, but wanted to put a few links out where new old-time music friends can find them today.
Sorry if there are spelling errors, and if you have to cut and paste the links into a browser. The first draft of this was done with my left thumb on a smartphone during a singing class at Augusta Heritage Center. (https://augustaheritagecenter.org)
Most of these are radio. Some are 1950s TV. The Delmore brothers sell their gospel song book, the Willis Brothers swing "Hillbilly Heaven." All Star Western Theatre combines accordion and guitar western harmonizing with short dramatic productions with cowboy movie stars of the forties. Pat Daniels Hillbilly Boys sold Hillbilly flour with Texas Swing, while Hank Williams sold Mother's Best flour with his country blues. Plenty here to explore.
https://archive.org/details/charlottecountry00holt Booklet PDF
https://archive.org/details/OTRR_The_Hillbilly_Boys_Singles (Pat O'Daniel & the...), 74 episodes