You did mention a “main drive”. I don’t know what’s taking all that space on your SSD but if you have a media library that takes some space you could move that to a connected HDD. While HDDs aren’t good as a boot drive it does the job well enough with most “standard” quality media. So can be said for documents and more obviously. You can then auto-mount your other drive to be inside your home directory for seemless access.
One thing that isn’t mentionned but I’ll just say this just in case. Always have external backups. I’ve scared myself way too many times thinking I had lost my main drive’s data just to find it the next day on one of my backup. Really a life saver if your setup has a problem where you find that one forum post from 12y ago with a “Nvm I fixed it” marked as [FIXED].
Other than that, thanks for sharing and with the solution at that.