I am here with providing partial answer of your question with " Praising of Upanishads" (upanishad Stuti , उपनिषद् स्तृती).
There is a chapter in Shreemad Bhagvad purana called "Veda Stuti" or Praising of Vedas. See chapter 87 ,Verse 3 , (Gita press Gorakgpur version) in which shree shuka deva is Praising Upanishadas. As -
सैषा हयुपनिषद ब्राह्मी पूर्वेषा पूर्वजै धृर्ता । श्रद्धया धारयेद
यस्तां क्षेमं गच्छेद किंश्चनः
Sesha Hyupanishad Brahmi Purvesham PurvajaiDhruta l Shradhyaha
Dharayed Shkemam GacheeddaKincshanaha ll
Meaning - Sanakadi Rishi ,who are ancestors of ancestors , accepted
this hign knowladge of Upanishadas ,which tells us about bhraman. Who
ever with devotion hear this ,gets freed from all the sins.