Here is the response I got from HubSpot yesterday:
"HubSpot has previously recommended to revert to one of the supported versions of Outlook for Mac.
This is a feature request that has been submitted (https://community.hubspot.com/t5/HubSpot-Ideas/Provide-Email-tracking-using-Outlook-for-Mac/idc-p/560063/highlight/true), and is something we will need to continue to work through with Microsoft directly (which can be rather difficult).
I definitely see why this would be a great feature to have. I will pass along this feedback to my team and I can also suggest reaching out and posting on our ideas forum: https://community.hubspot.com/t5/HubSpot-Ideas/idb-p/HubSpot_Ideas Here, customers are encouraged to post and vote on ideas as our developers will look to these ideas when making updates in the tool. I truly appreciate your patience and understanding here and I will also be sure to put this ticket through as a feature request."
At this point you might have better luck searching LinkedIn and trying to contact everyone that works for HubSpot that has an important sounding job title. At my previous job a co-worker told me he did something similiar to fix an issue he was working on for months with regular HubSpot support.