I will be located in a country where the Internet is EXTREMELY controlled and filtered. Not sure if I can even bring my current router with me(seems forbidden), so turning my RPi4 seems a good idea... Don't you think?
You'll need a USB 3.0 to gigabit ethernet adapter and a separate gigabit ethernet switch, but this setup is considered to be excellent as a lower-cost OpenWRT solution.
Alternatively you can use a managed switch and use vlan tagging, but this is slightly more complex and effectively makes the link half-duplex (up and down have to share the gigabit link, e.g. with a 100 mbit/s upload running you will be capped at 900 mbit/s download)