Double NAT port forwarding without access to main router, possible?

Hey,

So I just bought a new Synology NAS and while I was trying to set up port forwarding in my router (Google WiFi) I realized that it wasn’t working, so I checked my WAN IP address and it started with 192.168.xxx.xx I’m not good with networking stuff but it didn’t look like a WAN IP, so after some Google Search I think I found what my problem is... Double NAT.

Now my question is: is there any way for me to port forward some ports for my NAS without access to the other router? Anything at all?

Would appreciate any and all help I can get because it’s getting really frustrating, thank you!!!