Is there a way to block email tracking services on Apple's Mail app OTHER than blocking all remote images? Any extensions? I work in an industry context where I deal with numerous promoters who all love to include click tracking software on their emails (both for opening message/links), for example via MailChimp, Constant Contact, or YAMM.

Doing some preliminary research online, practically every solution within Apple's Mail is just to disable remote image loading. This isn't a convenient option for me as I'm dealing constantly with emails where I need to see information contained in formatted images etc.

Are there other solutions, extensions, hacks, anything to help block other parties' tracking services? 

In Gmail there are very capable browser extensions, but I'd like to keep everything in Apple Mail if possible.
I don't have an answer to your question. However I do have information that relates to this issue. 

Even though you might have images turned off on your mail, apparently Spotlight follows the urls during the indexing process, which negates the advantages of having the images turned off. 

So, you might want to turn off spotlight indexing of your mail. :( 

Link below.

https://lifehacker.com/disable-email-search-in-spotlight-to-avoid-message-trac-1678528323