Considering the size of the Montage screen, honestly, I don't think that reading pdf files from that screen would be a good idea. Most important, one would loose other functionalities which are more important: name of the performance and/or other performance data.
On the other side: using a tablet and an app like Setlist Maker is a perfect combination live. I still use a first gen. iPad for that purpose. And not only that, I use the iPad also for selecting my sounds by sending midi program change data. On press/tap and it changes to the desired performance while at the same time I can have lyrics and all other musical data on the tablet screen.

However, I would like to see Yamaha improving the Liveset Screen by allowing more than just 20 characters for notes. 20 characters is barely enough for a song/performance name, but for reminders (they appear on the bottom of the screen in the liveset screen) it is not enough while there is enough room for more than just a short 20 characters message.

Since memory area for this kind of data is limited - I've suggested using a USB stick as a way to store set list information so we could add more content and get the live set list closer to the amount of data afforded by other keyboards with a similar feature. Also, it may be possible to have the entire set list structure stored in a text file (user editable) which would allow for easier manipulation of the data such as rearranging, etc.

Previous post: https://www.yamahasynth.com/forum/please-improve-setlist-mode#reply-20039

Also mentioned that integration with a tablet (prefer either iOS or Android - using BLE and the MIDI adapter) would be great for a variety of features. Currently, there is already "Live Set" software out there for tablets which sees Bank/Program changes from MIDI and pulls up set list information - with many more than 20 characters. So you could go that route. The software is called "Set List Maker".

This software is not dedicated to Montage - it's generic.