M&M seem to be releasing new features on their website/app.
I received the same email as the one reported here by hugolover , and found these options below the (inoperable) Travel Insights:

Someone please correct me if I'm mistaken but I don't recall seeing these options in this format before. It would appear that M&M may begin to facilitate the online booking of eVoucher and award upgrades. When I clicked on the left, self-service, upgrade button, I found this portal with my future bookings displayed:

In typical LH IT fashion, this too is inoperable at the moment—all bookings show up yet display "your booking can not be found" within them—but I presume that at some point in the distant future, applicable flights might be able to be upgraded here. Following the logic of M&M online award flight bookings, I would assume that only upgrades that are instantly available would be possible online; I would be shocked if it let you do anything waitlist-related.