On 2 google accounts you can just server-side transfer it.
You can transfer the whole 750GB daily quota like this. There is no spesific server-side restriction (this was connected to a bug in apparently and has been corrected a long time ago). That should mean you should be able to transfer this is 50 days in so.
If you want a VPS to perform this transfer without running on your computer you can even set up a micro-instance on Google Cloud for free to do it It won't need to use any bandwidth, but you still need rclone to be running somewhere for maybe 30-60min each day to direct the traffic. If it is not convenient to run at home, just run the task at GCP.
Here is how to do this:
First we need to enable the feature, as it is not standard.
Either out this into your Gdrive remotes in the config file:
server_side_across_configs = true
or - use this flag:
(you do not need to enable it in both places. If you do then whatever your flag says will just override the config anyway).
When this is done - you can simple using normal rclone move/copy/sync commands between remotes - and when it is possible to server-side the operation then rclone will do so for you
rclone sync Gdrive1: Gdrive2:
rclone move Gdrive1:\ImportantFiles Gdrive2:\OldProjects
You might want to add -P so you can see the funny speeds you can achieve server-side
Common problems to be aware of when server-side copying:
If you run into 404 errors or what looks like permission-related errors, then it is highly likely that the users for each remote do not have access to the other drive. Even if rclone can do a server-side operation on two google accounts, the user in the remote still needs to actually have access to read the other drive. It is always the second drive in the command that is the active one. In other words - if you want to sync Gdrive1 to Gdrive2 then it is Gdrive2's user that needs to also have access to Gdrive1 also for this to be possible to do server-side.
There are many ways to solve these issues but the details depend on what types of accounts and what authentication style you use - so feel free to ask about that if you run into that problem