Gita Press Gorakhpur has published their books in PDF, digitized scan images in Public Domain. The problem I faced was they are huge in size. You can get those books from here https://archive.org/ search Gita press in the search option. It will show various files. Some are old and some are new. New scanned images are very high in size. e.g. https://archive.org/download/brahma-puran-gita-press-gorakhpur
The PDF is 1GB and _jp2.zip file is 561MB. I downloaded this zip and converted jp2 to jpg files and made PDF 72MB in size. Its good quality and has small size. I will slowly build other PDFs and upload them for others to download. Since the work is still in progress not all PDF are ready to download at present.
Original Purans are available here:
https://archive.org/details/@gitapress_gorakhpur
Files created by me are available here:
https://archive.org/details/@bindesh
List of files -
Agni Puran, 144MB (original 2GB)
https://archive.org/details/agni-puran-gita-press-gorakhpur_202204
Original: https://archive.org/details/agni-puran-gita-press-gorakhpur
Bhavishya Puran, 105MB (original 1.4GB)
https://archive.org/details/bhavishya-puran-gita-press-gorakhpur_202204
Original: https://archive.org/details/bhavishya-puran-gita-press-gorakhpur
Brahm Puran 72MB (original 1GB)
https://archive.org/details/brahma-puran-gita-press-gorakhpur_202204
Original: https://archive.org/details/brahma-puran-gita-press-gorakhpur
Brahma Vaivarta Puran, 136MB (original 1.8GB)
https://archive.org/details/brahma-vaivarta-puran_202204
Original: https://archive.org/download/brahma-vaivarta-puran-gita-press-gorakhpur
Garuda Puran, 104MB (original 1.5GB)
https://archive.org/details/garuda-puran_202204
Original: https://archive.org/download/garuda-puran-gita-press-gorakhpur
Kurm Puran, 73MB (original 1.1GB)
https://archive.org/details/kurma-puran
Original: https://archive.org/details/kurma-puran-illustrated-with-hindi-translations-gita-press-gorakhpur
Matsya Puran, 165MB (original 2.4GB)
https://archive.org/details/matsya-puran
Original: https://archive.org/download/matsya-puran-gita-press-gorakhpur
Narad Puran, 132MB (original 2.1GB)
https://archive.org/details/narada-puran
Original: https://archive.org/download/narada-puran-gita-press-gorakhpur
Narasimha Puran, 45.5MB (original 650MB)
https://archive.org/details/narasimha-puran_202204
Skand Puran, 246MB (original 3.3GB)
https://archive.org/details/skanda-puran_202204
Original: https://archive.org/download/skanda-puran-gita-press-gorakhpur
Vaman Puran, 71.9MB (original 1GB)
https://archive.org/details/vaman-puran
Original: https://archive.org/download/vaman-puran-illustrated-with-hindi-translations-gita-press-gorakhpur
Varah Puran, 63.5MB (original 890MB)
https://archive.org/details/varaha-puran
Original: https://archive.org/download/varaha-puran-illustrated-with-hindi-translations-gita-press-gorakhpur
Vishnu Puran, 81.7MB (original 1.1GB)
https://archive.org/details/vishnu-puran_202204
Original: https://archive.org/download/vishnu-puran-illustrated-with-hindi-translations-gita-press-gorakhpur
Here is link to how to make your own pdf like I did
https://ourinnovativemind.blogspot.com/2022/04/convert-images-in-batch-using-free.html