Reverse proxy on a virtual machine. It's safe?

Question

Network administration

Good afternoon. Help the lamer to set everything up correctly.
Initial data:
there is an api written by me on the backend server for 1s. Server on the local network behind the router. There is a mobile application that connects to api through a permanent vpn. Right now the connection is only via http. https in the future.
What I want to do:
Exclude vpn from this scheme
How I plan to do it:
Install virtualbox with ubuntu on the backend server. Raise nginx on it and configure a reverse proxy on it. virtual machine in dmz through a router.
Is this the normal option? or tell me please how to do it right.
A simple router. open only for vpn. firewall on the front by itself. http traffic only.
On hosting, of course, it's good and right. But it costs money. So far it's not worth it. Therefore, it is interesting about the virtual machine.

Answer 1

If the router does not have vulnerabilities and the DMZ will be only the address of this virtual machine and access to this virtual machine will be blocked (which you did not mention) anywhere except outside the router and the API - then completely.