I think NULL_SUB address is fine, current address and the suggested, are equivalent (100a and 101a):
/*************************************************************/
//** sub_FF810B64_my @ 0xFF810B64 - 0xFF810B68, length=2
void __attribute__((naked,noinline)) sub_FF810B64_my() {
asm volatile (
" BX LR \n"
);
/*************************************************************/
//** sub_FFFF19F4_my @ 0xFFFF19F4 - 0xFFFF19F4, length=1
void __attribute__((naked,noinline)) sub_FFFF19F4_my() {
asm volatile (
" BX LR \n"
);