How to move files from iCloud to Google Drive efficiently?

Question

I currently store my desktop and documents on my Mac using iCloud. I want to only keep my desktop in the cloud, and I know there is no way to do that using iCloud, so I want to make the switch to Google Drive (plus it's cheaper).

I have already downloaded the Google Drive client and have synced everything on my desktop with Google Drive, as well as moved all of my photos to Google Photos. The issue now is disabling iCloud. Apparently when I disable desktop/documents on iCloud, it removes all of the files from my computer and stores them exclusively in iCloud, which is the opposite of what I want. I have looked up how to disable desktop/documents on iCloud while keeping the files on my computer, and nearly everyone is saying to disable it and redownload the files, which I really want to avoid doing.

My ideas for how to proceed are the following:

1. Disable desktop/documents syncing on iCloud and then download everything from iCloud (Concerns: This will take quite a while, and I'm pretty sure it would remove everything from Google Drive when they're removed from my computer, and require me to reupload them, which took 5.5 hours last time, plus I'm a little eerie about having my files removed from my computer)

2. Copy all of my files to an external hard drive, disable desktop/documents on iCloud, and then move everything from the hard drive to my computer (Concerns: I think this would also require me to re-upload everything to Google Drive as well, and I'm not entirely sure how I would move only my desktop and documents to my hard drive)

3. Pause syncing with Google Drive, disable desktop/documents on iCloud, and then download everything from Google Drive (Concerns: I'm not sure if Google Drive would delete everything when I resume syncing).

If anyone has an opinion about which option is best, or if you have a better solution, I would greatly appreciate it. Ideally I just want to disable iCloud entirely and keep the files on my computer and in Google Drive, but I'm not sure how to do this efficiently and safely (not risking losing my data).

I have a 1TB external hard drive ready to use, so if there's a way I can use it to speed up the process, I would prefer that.