I have used Microsoft Access to generate the following (draft) layout. This specific layout is optimised for the dimensions of my iPad Pro. I simply generate in Lr the images for a specific trip or event and use Access to generate the pdf and import it as a PDF into the iPad Book app. The result is that I have a superb, easily accessible book/slideshow, etc of my trip, with relevant meta data professionally placed relative to the left and right edges of the frame. This is still work in progress, with some tweaking required. Excuse any typos.... just using some test data.
I had a lot of tweaking to do to ensure I was getting the native jpgs embedded in the document, but I am very happy with the resultant output on my ipad.
My next step is to do a version for A5/A4 printed output. I plan to print to good quality paper and use wire binding to produce adhoc books or draft versions of books for more professional binding. I will compare the quality of prints using the generated PDF to actual colour managed prints on my printer.
I have also purchased the Report Generator module of the MatLab software. I have to learn how to use this... but this (hopefully) will be my final solution. My MatLab app will have a simple form where I press a button to select a folder of preprepared images in a folder from Lightroom. I will have multi choice boxes to select the format required (eg iPhone, iPad Mini, Ipad Pro, A5, A4, A3, etc. MatLab will then automatically create a page per image, generate a full PDF, with the Image and related metadata precisely placed relative to the size of the image. I can set PDF security settings to protect the integrity of the document created. Matlab will extract the metadata from the images themselves, so I do not have the hassle of any third party data merge software. MatLab Report Generator will also allow me to create Powerpoint slides, Word Documents, Html pages, etc. I can use pre-prepared Powerpoint templates, with logos, transitions, animations etc fully automated.
I am fed up waiting for Adobe to allow me place images and metadata on a page layout in a professional and efficient manner. Using MatLab gives me access to a modern platform which allows me to combine my images and metadata in a meaningful way. The MatLab platform has every possibility of outlasting my needs into the future.
Again, I would prefer to do this inside the Adobe ecosystem, but I have lost patience and can see a solution which will work for me and has legs for future refinement as my workflow or technology evolves.