No, we don’t need a local backup anywhere in the process. A backup is only needed as safety net, in case something goes wrong.:
This was succesfully tested by 2 volunteers, as mentioned in that post.
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That’s description is just not true! Maybe they try to scare folks to keep them for installing experimental updates ‘just for fun’, I don’t know.
Because of the time of writing that ‘guide’ it was before 2020, and with a Pro 2016-2019 you’ll need to restart to recovery mode and restore a backup. Even then a factory reset was not part of the procedure..
The procedures I wrote, for both pre- and post 2020 models, were tested by two volunteers with a Pro 2023 at the time of writing, and by me in the meantime, since last december.