1. add this to /var/lib/snapd/apparmor/profiles/snap.chromium.chromium:

audit deny capability mknod,

2. Load the policy with: sudo apparmor_parser -r /var/lib/snapd/apparmor/profiles/snap.chromium.chromium

3. add this to /var/lib/snapd/seccomp/bpf/snap.chromium.chromium.src:

mknod - |S_IFCHR
mknodat - - |S_IFCHR

4. compile the policy with: sudo /snap/core/current/usr/lib/snapd/snap-seccomp compile /var/lib/snapd/seccomp/bpf/snap.chromium.chromium.src /var/lib/snapd/seccomp/bpf/snap.chromium.chromium.bin

5. strace with: sudo strace -u <your username> -e '!select,pselect6,_newselect,clock_gettime' -f -D -vv -o ./chromium.trace3 /snap/bin/chromium