None of the local ISPs supports WAN Aggregation since the ONT/ONR do not support IEEE 802.11ad.
https://www.asus.com/sg/support/faq/1039053/
For local ISPs using unbridged ONR, or using dual 1Gbps plans, then there is a possibility to use Dual WAN Load Balancing.
https://www.asus.com/sg/support/faq/1011719/
However, based on the report here, there is only one LAN port activated for the VQ bridged ONR. So there will be no support of Dual WAN Load balancing either.
You may want to go with an 2.5G capable router and use the 3Gbps plan as a true 2.5Gbps plan. In that case, I will suggest to go with the good ones with dual 2.5G ports. For example, you can go with things like Asus GT-AX6000, Asus TUF-AX6000 (or the China version TX-AX6000), GL.iNET MT-6000, etc, depending on your budget.