I know this is OT but you have to bring up Cisco 😉
I was a full time Cisco engineer in my previous work life. I still own a couple of 2nd hand Cisco gear I use at home.... Cisco 2621XM for the IP phones and a 3560G switch for L-3 inter-VLAN routing.... They're old by today's standards, but still quite capable and more importantly, cheap for home use. Also used Cisco Aironet 1200 series APs, also 2nd hand, way back when businesses were migrating to 802.11n.
Cisco nut, that I was... and to a certain degree, still am. I've been holding on to my Cisco certs for almost 20 years now and counting.
Then around 5 years ago, I pulled the trigger and bought UniFi APs.
All I can say is, we are a big family with tons of IoT devices...
I brought up Ubiquiti because it's the AP I've been using in the last several years that has band steering. As of late, this feature has been trickling down to other consumer WiFi equipment like TP-Link's Omada, D-Link, Asus (they call it Smart Connect), just to name a few. Even open-source router OSs like DD-WRT has it, well, to a certain degree. In fact, the OP may already own a router that supports it.
Just saying that using different SSIDs for each band may not even be necessary with today's 'magic box' APs.