Change login wallpaper in macOS Big Sur?

Because I like to personalise my Mac I prefer to use my own login wallpaper (instead of the one set by Apple).

On Catalina I followed this procedure and all was fine.

On Big Sur there’s this procedure, but with serious consequences!

(indeed my spare Mac, on which I experimented with this, now refuses to boot without SSV disabled…)

(How) Can I change the login wallpaper, while keeping SSV enabled?

Note: this Mac has FileVault enabled, has multiple users configured, and is under MDM control…

Hey, that’s my StackExchange question! :slight_smile:

Unfortunately, I think the answer is “You can’t.”

Even Mac Pilot, which prides itself on cataloging all of the obscure things you can do to your Mac, has dropped this feature for Catalina and beyond.