You may, but it won't run because it's not signed.You may recompile source code.
Splash data: https://github.com/Atmosphere-NX/Atmosphere/blob/master/sept/sept-secondary/src/splash.c#L26
Size and pos: https://github.com/Atmosphere-NX/Atmosphere/blob/master/sept/sept-secondary/src/splash.c#L47
You cannot.I use Atmosphere and will change the sept bootscreen. It is possible?
This is correct, however the vulnerability used to dump the key is public now so if someone is willing to go through the effort of writing a payload to do it we can get what is needed to sign sept ourselves.You may, but it won't run because it's not signed.