Since Layout Builder was added to Drupal core in 8.5, Lightning has had plans to adopt it and retire Panels and Panelizer. We've been working hard at closing the feature gap between out of the box Layout Builder and what Lightning Layout currently provides. At the same time, we've added some significant new features to Layout and made massive architectural changes to the storage of blocks created as part of a layout.
Here's a quick peek at creating a landing page using the Lightning Layout.
Note that this branch of Lightning and Lightning Layout are both alpha stability. We're hoping for beta stability this winter and a full release with a migration path early next year. This graphic shows the high-level features of each branch.

Resources
- Lightning Profile 4.0.0-alpha2 sandbox (uses Lightning Layout 2.0.0-alpha2 - un/pw admin/admin):
https://lightning.acquia.com/lightning/4.x - Lightning Layout 2.0.0-alpha2 (uses Layout Builder):
https://www.drupal.org/project/lightning_layout/releases/8.x-2.0-alpha2 - Scaffold Project instructions:
$ composer create-project acquia/lightning-project MYPROJECT
$ cd MYPROJECT
$ composer require acquia/lightning:4.0.0-alpha2 --no-update
$ composer update
# Install Drupal as you would normally.