Is it possible for a 2020 iMac to go back to Big Sur or Mojave?

[migre]

I want to downgrade from Sonoma to one of those 2.

 

[chrfr]

I want to downgrade from Sonoma to one of those 2.

A 2020 iMac can't run anything before Catalina 10.15.6. Big Sur will not be a problem for a downgrade.

 

[migre]

Can 2019 iMac run Mojave?

 

[PaulD-UK]

Yes. I've got an external Mojave boot SSD.

 

[migre]

Yes. I've got an external Mojave boot SSD.

Interesting. What do you use the Mojave for?

 

[PaulD-UK]

I don't use it much these days, but had it from the Catalina/problem era. It still boots and runs fine.