How to put a signature and print on .pdf, jpg, gif files on android?

Question

Android

Need a program for android that allows you to put a signature and PRINT on pdf, jpg, gif files. On the PC I use the program "for signature" (a program specialized for these purposes), I did not find something similar on android. Programs like "hellosign" allow you to put only a signature, and even then by drawing it with your finger, and this is immediately noticeable.
If the program does not exist in nature, this option may be: if the file comes in pdf, we convert it to jpg or gif (we need a program), then insert a signature and stamp on the drawing with a graphic editor (which graphic editor is suitable?).
It’s tricky, of course, but what to do, you need to look for a way out!
Maybe there is an easier way?
Thanks in advance for your advice!!!