The 40MB RAW DNG still photos from the
M2P will always be far superior for large format printing than any still frame grabs from the 4K video, assuming you captured the precise framing you wanted in a still format DNG. Even your lossless TIFF saved video frame grab was only 30MB in size, but was just the equivalent of a large format internegative taken of a print, when you no longer have access to the original negative.
Nothing you have previously learned about photography and video changes just because the camera is now on a flying tripod. Hence, our surprise that you assumed it did, and your assumption that you merely lacked experience at drone flying to understand the basics of photography. Hopefully, we have cleared that up for you. Everything photographically is still the same, when it comes to how to capture the best image for large format printing. Capture the largest original image with the most data possible. That will always be a still DNG, and not a 4K video frame grab.