Yes, exactly—not many people know about Chainer nowadays. Back in 2016, PyTorch's interface was actually inferior to Chainer's, and I think Chainer's design was really ahead of its time.
Wondering how this compares to Emacs org mode, which support exports to PDF slides with beamer or plain PDF document, also support to export to lots of other format. It also allows running the embedded code and export the results. Of course embedding PDF is easy.