I'd like to migrate all my various google accounts into one so I don't have to remember five different ones (and also, some of these are kind of tasteless names that I made when I was a 14). The problem is that I don't want to risk losing my precious subscriptions by having to migrate them all manually. I have some basic python knowledge if there is an API i'll have to use to get this done.
This program can be used online to transfer subscriptions. The GitHub page has step-by-step instructions, as well as a link to video instructions.
This program can also be used online. Instructions are included on the web page, as well as a link to JSFiddle where the code is hosted.
The first option was last updated 3 years ago, and the second option was last updated almost 6 years ago, but both are free and worth a shot.
If you want to try to code your own solution, here's a link to the Subscriptions section of the YouTube API:
So I finally figured this out, and I turned out it didn't need a tech solution. I was unable to make much progress with the scripts because Google limits you to 80ish new subscriptions per day and I kept hitting that.
It turns out that the actual YouTube account that has subscriptions and playlists is a "brand account" which is owned by a Google account.
Basically to move your brand account, you can add another Google account as a co-owner of your brand account, in the advanced account settings, after clicking "manage permissions". Add the Google account that you want to move subscriptions to. After 24 hours you can use the destination account to change that setting again to make it the primary owner. Then you can remove access from the first account, and your subscriptions are now moved.
Comments and watch history don't seem to have been moved but that wasn't a problem for my case.