A commenter already provided a fairly comprehensive description of low-level computer security positions. But I also want to note that a firm foundation in low-level implementations is also useful for designing embedded software and firmware.

As in, writing or deploying against custom BIOS/UEFI images, or for real-time devices where timing is of the essence. Most anyone dealing with an RTOS or kernel drivers or protocol buses will necessarily require an understanding of both the hardware architecture plus the programming language available to them. And if that appeals to you, you might consider looking into embedded software development.

The field spans anything from writing the control loop for washing machines, to managing data exchange between multiple video co-processors onboard a flying drone to identify and avoid collisions, to negotiating the protocol to set up a 400 Gbps optical transceiver to shoot a laser down 40 km of fibre.

If something "thinks" but doesn't have a monitor and keyboard, it's likely to have one or more processors running embedded software. Look around the room you're in and see what this field has enabled.