"how to identify 'system files' when using 'smart folders' to group 'file extensions'

i’ve been in the process of making ‘bulk transfers’ from ‘macbook’ to ‘google drive’. i had been using ‘smart foldes’ as an organizational tool to group files by ‘file extension’ and them dump them all in my ‘google drive folder’ assigned to that particular file extension.

search for all .MKV files on ‘macbook'...

drag/drop them into ‘google drive’'...

then delete the files from my macbook to save space.

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for years i thought that ‘google backup + sync’ would do as they promised

but no matter how many times i changed settings and made sure that the sync shouldn’t go both ways, my macbook would start filling up anyway.

i thought the ‘smart folder’ filter was a good way to streamline the manual transfer.

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i would just double-check all transfers to ensure that the process was complete and then delete those files off my macbook.

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then i ran into a snag when creating a macbook ‘smart folder’ for all ‘text files’ and dumping them into google drive. i realized that i had just come dangerously close to deleting all those text files that could have been ‘system files’ deleted.

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is there any way to identify ‘system files’ that should never be deleted? i know that there is a hidden libraries folder that holds important files, but would a ‘smart folder’ be able to include those files as visible 'search results'?

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what would have happened if i had deleted all files in a ‘.txt smart folder’?

(i was recklessly using the ‘command/option/delete’ shortcut that circumvents the ‘trash bin’)