I wonder how flexible is the SQLite binary format to allow to design a tool that would take a SELF binary/db and rewrite it to make BLOB values more mmap-able (OS page aligned) in order to allow shortcuts in the self-exec loader.

You'd have to at least increase the page size to allow 4kB of consecutive data without interfering with the page header.

OR you restructure the code and data to work around the page headers.