As xonix mentioned, you can use Dual WAN Load Balancing to achieve single network if your router supports this function.
From the other thread you seem to use TP-Link Deco XE75, which will not support Dual WAN Load Balanding.
AXE5400 Tri-Band Mesh Wi-Fi 6E System
The AXE5400 WiFi 6E Mesh WiFi System boosts your WiFi range and delivers ultra-fast WiFi speeds of up to 5400 Mbps.
www.tp-link.com
Example of routers with Dual WAN Load Balancing and 2.5G port to fully utilize the capability of your 2Gbps plan: good performance price ratio will be GT-AX6000.
Or you can get low power mini PC with dual or quad 2.5G ports, then you can run OpenWRT or pfSense with good Dual WAN support. They will have better Dual WAN capability than the Asus GT-AX6000. Then you can still use your Deco XE75 as mesh (AP mode).
Asus Dual WAN Load Balancing
[Wireless Router] Dual WAN introduction and setup - Failover and Load Balance | Official Support | ASUS Global