Interesting, I hadn't thought of a "color" solution, thanks! But even with this color based solution the generated file would still be very large (because it would list the files as well).
I actually already had a plan b, but I hoped there would be a simpler solution.
I'll probably have to create a script that does something like:
run a lsd and point to a controlled output;
run a size for each of the above output lines, generating an output "report".
It only shows the folders and takes less than a minute on my GoogleDrive with app. 50.000 files.
This is faster than measuring the folders individually due to less overhead to start rclone, establish connection, login, etc. It may be even faster with --fast-list.
If you like coding (data parsing and accumulation), then you may want to consider lsf or lsjson with --recursive - again you will get all the data in a single Go - no pun intended