It’s said that he was better on the autoharp that the banjo. There is a album he did on YouTube, one side is all banjo and the other side is all autoharp. Old school bluegrass isn’t for everyone but has a special place in my heart.
I thought I recognized parts of the progression. Not a lot of songs go to the 4 then it's minor. When I hear a song I usually can think of several that are the same progression or close to it. Sometimes it's hard to play a song with the same progression and not make it sound like another song. At least in bluegrass anyway.@Benjo75 Ben, You might notice the chords are roughly a rearrangement of the progression to the Don Stover banjo tune Black Diamond