I've got the ideas, content, and writing, but I don't know what people actually use to make the PDFs. Is it like, google docs and then turning that into a pdf, or do you pay for the Adobe Acrobat and/or Microsoft Word stuff? A website maybe?
I currently use Affinity Publisher, in the past I've done layout entirely with html & css ;-). Tried Scribus once and didn't know what I was doing, though that was probably inexperience and time pressure.
There's no shame in using Word or Google Docs though! IIRC Maze Rats was laid up entirely in Word, and it's one of my go-to examples of great, if understated, layout.
(youtube video linked since the itch page doesn't have any screenshots of the booklet)