Is it a big deal if I use Big Sur instead if El Capitan which is the initial MacOS support for me?

I've been told I should be good with Big Sur on my specs but sanity checker is telling me

• SystemProductName = iMac19,1 this is not a suggested SMBIOS for Skylake Desktop systems. See PlatformInfo Docs

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Also, I'm getting this error:

Output

• You should have exactly 12 settings in the UEFI/Output section

I counted 12 settings in the config so I don't know why it doesn't go away.

Also:
SystemUUID should be set to your generated SmUUID. See the PlaformInfo Docs

But I've seen someone mention that this error isn't important as it will be done after the installation, is that true?
Thanks.