Searching for router to buy

Well, good for you ;). Now, with a Gigabit link two concurrent video conferences will not be enough, but 2 video conferences with a number of concurrent downloads might, but I accept that for your use caes that situation simply does not happen.

Not necessarily a raspberry pi4b for example has enough CPU cycles to run SQM at 1 Gbps, and costs around 100 EUR with the required USB3-ethernet dongle, or use the raspberry pi4b compute module with the dfrobot gigabit router carrier. You will end up with a gigabit capable wire only router for around 100EUR, which will require an addition managed switch and/or another openwrt router as AP (the pi's build in wreless is not router-class).
I do not want to push you to try this, I just want to counter the narrative that traffic shaping @1Gbps is territory of higher end x86 alone...