Is Alsoft working on a version 6 of DiskWarrior that can rebuild SSDs with Apple’s APFS?

Yes, Alsoft has stated that the next major release of DiskWarrior, version 6.0, will include the ability to rebuild APFS disks. 

Apple released a majority of the APFS format documentation in June 2020, and Alsoft's developers are using this documentation to update DiskWarrior to safely rebuild APFS disks. 

It's important to note that DiskWarrior 5.3 and earlier versions do not support rebuilding APFS disks. The startup disk of Macs running macOS 10.13 High Sierra and later versions with SSDs automatically use APFS and therefore cannot be rebuilt by current versions of DiskWarrior. However, DiskWarrior can still rebuild external drives formatted with Mac OS Extended (HFS Plus). You can also join the Alsoft Mailing List to be notified of progress regarding APFS support and updates to DiskWarrior.