That would be a huge undertaking unless it is something very simple. Fortunately BIOS can do a lot of work for you, you only got to implement file access and work in memory management and related to any user programs. OS itself might not be that hard but making the software will be another level of headache that is gonna take a while to go away. Without any previous embedded programming experience you'll be in for a world of hurt 🤣.

https://wiki.osdev.org/Main_Page

nice, thanks for the link BloodyCactus
Tiido: I've reading that using bios interrupts is not as good as it sounds, at least in the long run, because they're not exactly standardized, i will be reading more about that

if you want protected mode + use all the memory, forget bios. if you want 'dos' real mode only, 640kb, bios is fine.

If you skip the bios, you need to know the chipsets in your laptop (what its using for IDE maybe, what its using for video, sound etc), you will have to write your drivers.