To me labels breaks imap and other standard protocols. Some apps have built in work arounds as so many use Gmail, but since I use my own domain (fastmail) I want to use any app to access it. I use Apple Mail as it does enough for me, but if I jump on a Windows machine I would suffer no consequence for using Thunderbird, Outlook, or Windows Mail.
I am surprised no one has yet mentioned Mimestream. This might be EXACTLY what you’re looking for, rather than fighting Apple Mail. It’s built specifically for Gmail, and is made by. former Apple software engineer. I love it for Gmail.
Thunderbird supports both tags and folders. Whether the tags propagate to the gmail server, I don’t know. I don’t think they do, but they work fine for my purposes as-is.
In Thunderbird, one can place email into a folder, and also add zero or more tags. In Thunderbird, these are not mutually exclusive.
Gmail Labels aren’t tags, that’s for sure. As far as I know, Thunderbird tags don’t propagate back to Gmail.
Just reading this. You and @ibuys seem to have a great sense of humor. lol. 
Plus I learned stuff about Mail
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