>Should I continue working on low level projects and hopefully they are good enough, or there are other approaches?
The way i had done this in the past was to really learn the language well (today you will also have a GitHub repo of projects to show), practice algorithms/data structures/interview questions in C/C++ and finally, understand the tight coupling between C/C++ and underlying OS i.e. "Systems Programming". This is the preparation phase.
In the execution phase, you contact companies/recruiters/friends/anybody at all with suitable openings and make it very clear that you really really want the job even if it means taking a pay cut i.e. Salary/Money should not be the goal. Make it clear and open that you are looking for a break into that domain and you are willing to put in any Time and Effort reqd. Finally, try smaller companies rather than big ones at first; their requirements are less strict.
HTH