Compressing to PVR will not give any benefit because most devices just don’t support this compression type. Compressing PNG is OK, I’m sure that most files can be compresed to PNG8 or PNG8 dithered).
Btw, sort resources by decreasing file size in file manager. What kind of resources has biggest size per file? Are there resources like 100 small similar pictures?
P.S. It’s better to not try to split file on several parts because mobile games should have nice quality to attract users. There’s nothing good in 300 or even 100 MB of resources.