How best to update from Mojave to Big Sur

I have loved using TuneSpan over the years and have recommended it to others, but am thinking of updating to Big Sur on the Mac. I have almost all my music and all my movies spanned to a RAID drive mainly due to the fact that my iMac does not have the space on the built in SSD to contain them. I noted that you recommended Unspanning the library before updating, but that is physically impossible due to size constraints. I do not want to lose my playlists for the music, and I can move the movies manually, but is it safe to do the update? Is there a step-by-step process others have done in this situation that works?