The short answer is

Instead of accurately mimicking the exact hardware structure of the PSP (which would require the original BIOS code), the creator of PPSSPP (Henrik Rydgård) and his team reverse-engineered the PSP’s internal functions.

Many PSP games use Sony’s proprietary system fonts to display in-game text, dialogue boxes, and user interfaces.

in your games (a common issue sometimes confused with BIOS problems): System Fonts:

: Extract the portable zip version to a folder. Create a subfolder named PSP games to keep your ROMs organized.

Ideal for budget or older Android smartphones.

Let’s clear up the confusion once and for all.