Think I may have it resolved. Time will tell for sure but looking good so far.
After adding the push route-metric and route, the interface network category was still set as "Public".
But then after setting the network category to "Private", using the "Set-NetConnectionProfile" command it seems to stick with future connections. So we'll see how well that holds up over time.
I consolidated the two push commands into a single command of:
push "route 0.0.0.0 0.0.0.0 vpn_gateway 9999"Any gotchas lurking with the single command? OpenVPN doc does mention the "vpn_gateway" keyword may not be compatible with all OS's. But didn't mention any specifically.
Thanks to everyone for your help and getting me on the right path.