I also wrote a little Python tool that iterates through syscall tracepoint declarations in debugfs (/sys/kernel/debug) and lists available syscalls and their arguments available in your currently running system:
https://tanelpoder.com/posts/list-linux-system-call-argument...
Debugfs does not show platform-specific syscall internal numbers though (but the stable syscall IDs).
Apparently debugfs does not show all syscalls, excluding "some weird ones" as mentioned by mebeim/systrack author in an earlier HN discussion: