seedutil
Enroll macOS Beta Seed without profile installation
Usage
$ sudo /System/Library/PrivateFrameworks/Seeding.framework/Versions/A/Resources/seedutil
usage: seedutil enroll SEED_PROGRAM
seedutil unenroll
seedutil current
seedutil migrate OLD_VERSION NEW_VERSION
seedutil fixup
Enroll DeveloperSeed (Developer Beta)
sudo /System/Library/PrivateFrameworks/Seeding.framework/Versions/A/Resources/seedutil enroll DeveloperSeed
Enroll PublicSeed (Public Beta)
sudo /System/Library/PrivateFrameworks/Seeding.framework/Versions/A/Resources/seedutil enroll PublicSeed
Unenroll Seed
sudo /System/Library/PrivateFrameworks/Seeding.framework/Versions/A/Resources/seedutil unenroll
See enrolled Seed
sudo /System/Library/PrivateFrameworks/Seeding.framework/Versions/A/Resources/seedutil current
Some time ago, I generated a small Apple script based UI for this, which might be useful for some.