Should I include interviews transcriptions in my thesis? In my PhD, I ran an experiment falling within the grounded theory framework, based on interviews I conducted. I transcripted them, tagged them, etc. This "enhanced transcription" is about 130 pages long (with pretty narrow margins).
I am now writing my thesis and I wonder if I should include these transcription in appendix of my PhD thesis.

My first guess would be yes, in order to enable contextualization when I quote snippets of theses interviews, but also for "open science" purposes (being honest about what I've done, archival purpose, reproducible research, etc.).

However, thesis in my field are usually ca. 150 pages long. Addind these transcriptions (i.e. 130 pages) would add a significant amount a pages with a low information density. A solution could be to display these transcripts in a very small font, so that they are only 50 pages long, but I don't think it's a good solution.

By the way, my supervisors don't have opinion about it, since using grounded theory is rather uncommon in my field - hence no "jurisprudence".
Quite honestly I doubt that anybody would go and read that appendix. What I would do is that once the thesis is approved and put in the online repository of the university, you could add this appendix just as an online document and refer to it in the main thesis. That way if anybody wants to access it they can.