A large number of old Opry radio shows are available on Internet Archive, but I just found that dozens of episodes were uploaded to YouTube this month: https://www.youtube.com/playlist?list=PLlFHypGTH4En2lfWoSB0wsFMIecXVStl8
So far, the episodes on this YouTube list are from 1939-1956.
Also, I found a playlist of the Gannaway Opry shows from the 1950s: https://www.youtube.com/playlist?list=PLyopL49unRu8I_YM7JHxTwiIDjwndRth8
RFD-TV shows full episodes of the Gannaway shows.
My 1950s Country TV Shows list includes some Opry and other cool shows: https://www.youtube.com/playlist?list=PLkY8-UOMZQ08xEU_XeDtBzGS2him_-cln