Using VRF
We found a eligant for instead option for ifupdown. Which is ifupdown-ng.
Try this out.
In the service
+++
ExecStart=/usr/sbin/ip vrf exec $[Your VRF Interface]
#Add Capabilities if using no root user.
AmbientCapabilities=CAP_SYS_ADMIN CAP_NET_ADMIN CAP_DAC_OVERRIDE