Hi , that really depend on how you LAN setting is , i presume a typical LAN setting with a WIFI router and your LAN is connected to the internet so your PI is connected to the LAN. the idea is similar like the image i shared , but is good enough to explain ,

Network connection diagram

 consider that . Our Laptop / Other Laptop one of this is your PI and  Website is your Odoo server at your Digital ocean and you have full server access that can allow you to configure the network access , then you have 2 way to allow connections , secure and unencrypted , for unencrypted connection , you have to set  port forwarding to your PI at yout WIFI router (public wifi , which is your LAN wifi router ) , and for secure tunnel , either you know how to setup reverse SSH tunneling, there are lots of documents you can find out , just googling it or you can simply use a free service offer by NGROK to allow SSL Tunneling behind your firewall / wifi routers. you can go to NGROK.com to view , there is lots of documents on how to setup.

Cheers !