Anyway thanks for the feedback, in this case i would like to stick with a all in one router for simplicity, space and power consumption. I would sacrifice those 100mbps on wireguard if there is something fitting the bill.
If mt7621 actually does combined 200 Mbps wireguard I am not confident there are any CPU cycles left for traffic-shaping (required for sqm). I would go for one of the arm a7x devices, like:
this has arm a72 cores (and weaker but more efficient a53s) that should do what you want (so wireguard and sqm at your desired rates), modulo the WiFi for ~ $70 (plus shipping and VAT?). This can be paired with a cheap OpenWrt capable AP to get the "missing" switch ports and WiFi.
The * MT7621s ~900 MHz MIPS cores are really getting long in the tooth, plenty good enough for an AP, but not really for a primary router at 100/100 Mbps unless no additional services are desired/required.... my 5 cents...