Uhh I don't see this ever getting packaged. Development is slow and relies on GCJ for compilation. That is the GNU Java Compiler and I am fairly certain it is no longer actively developed. There is a reason they only provide official builds for Red Hat/CentOS. Apparently its being rewritten w/o reliance on GCJ but I have little hope of this ever happening. Here is the issue with more information https://github.com/documentcloud/docsplit/issues/123. Poorly managed software.

My work flow relied on pdftk heavily. I wanted to compile it on solus and submit a patch. But I gave up when I saw GCJ dependency.

I am currently using ghostscript as a replacement, after searching extensively on stackoverflow for replacements.
cpdf looks promising, but it has a non-commercial license. Is solus against packaging software with this type of license?

I sincerely hope we can find some replacement for pdftk, spliting/merging/watermarking pdf files is essential to me in processing business documents.

Just wanted to let everyone know that there is a flatpak build available as of late.
https://github.com/egrath/pdftk-flatpak

There is also a snap, which I installed instead of the flatpak because I admit I am quite awkward with the dependencies of flatpaks and do not fully understand how the system works. I would recommend installing using snap install pdftk instead of sudo snap install pdftk though, as opposed to what is written in the pdftk snap page, to avoid any $PATH issue.