How do I make a python aiohttp server hosted on virtualbox available?

I looked around but I although I saw a lot of similar questions, none is the same and none have solved my issue. I have a python server built with aiohttp. I works just fine when running on localhost.

Now I am considering accessing it from a distant machine. I however do not have access to that machine at the current time so I decided to develop my server using virtualbox to simulate having two machines.

I don't understand how I am supposed to access it from the real computer though. The issue is double:

• how does one render an aiohttp server available from a distance, in general?
• does the fact that I am running it on virtualbox change anything?

Here is the code I believe to be relevant:

import socketio
from aiohttp import web 
...
_server = socketio.AsyncServer(async_mode = "aiohttp")
_app = web.Application()
_server.attach(_app)
...

async def index(request):
    if request.method == "POST":
        data = await request.json()
        return web.json_response(await process_request(data))
    return web.json_response({"Unsupported method": request.method})
...
_app.router.add_post("/", name="index", handler=index)
...
web.run_app(_app, port=port, host="0.0.0.0")

My virtual machine runs on a Debian 10 image. I have tried forwarding its ports to those of my real machine, with no success. Its network adapter 1 is set to NAT.

Also I'm a total noob with this so if you see something in my code that seems like a bad habit do not hesitate to tell me in the comments :D

Thanks