Rotate your phone into landscape mode and it is much easier to read manuals with vertical scrolling instead of V+H scrolling
PDF parsing in general is a hard problem because PDF is an encapsulation of PostScript, which is Turing-complete.
HOWEVER, for a particular document / process, you may be able to build a special case parser that will work until something changes in Elektron’s documentation toolchain.
If you intended to do this manually, use it as a portfolio piece to land a tech writer / doc ops job that pays well
Your intentions seem pure, but it is difficult to see this as anything other than a great gift to SEO spammers.
You can get a budget 27" monitor for under USD$150. Add a small Raspberry Pi and a mouse and keyboard you already have and you can have a dedicated document reader for ~USD$200
I’m sad that Letter / A4 size eInk displays don’t sell in the volume that 6" eInk readers do and thus are still too expensive to spam across my office.