hello jjsalzano,
Uboot already has a feature called Verified Boot. There is already a tool to sign the binary In Uboot source code.
you may see-also below for reference.
[U-Boot] Need help with verified u-boot on Tegra TX2
https://blog.crysys.hu/2018/06/verified-boot-on-the-raspberry-pi/
you may see-also similar discussion thread, Kernel encryption through Secureboot - #12 by JerryChang.
thanks