Turning on FileVault with a symlinked directory

Running Mojave (10.14.6). There's not enough room on my SSD for my Music, Pictures, and Movies. I have those on an external drive. I have not yet turned on FileVault. If I create symlinks for those folders in my home directory on the SSD pointing to the external drive, will there be any issue when I turn on FileVault? Will only the SSD folders get encrypted, or also the symlinked folders? And related question: will Time Machine automatically include those symlinked folders?

I've seen elsewhere the advice to just move the entire home folder to the external drive, but I want to keep it on the SSD to speed app launching (among other things).

FileVault only encrypts one volume so hard links and firm links are encrypted (but firm links are portals to another volume which isn’t necessarily encrypted). Symbolic links exist on the volume and are encrypted, but their destination files are not encrypted - just the link to the other file is encrypted.

Your plan to move some folders off is just fine, solid technically and you can encrypt both volumes using FileVault and keep everything encrypted at rest - just that there are two different volumes with different keys and you choose if you use the same or different pass phrases for both.