Apologies for being late to the thread.
I use pfSense, which has a common lineage with OPNsense. The router is followed with a manged switch (D-Link DGS-1510), which may not be necessary if the router/firewall host has enough NIC ports for your application.
For the Wi-Fi, I use an access point made by TP-LInk (EAP 245). You don’t necessarily need a controller (in the Cloud for UniFi) unless two or more access points are meshed. The controller can be hosted locally on Linux or Windows. Mine is hosted on my desktop PC.
Any of these functions can be mixed and matched with heterogeneous hardware, but the downside is the learning curve of a unique user interface for each function. Moreover, configuration can be arcane at first unless you have a background in networking. FWIW, I’m still learning.
Here’s a company providing off-the-shelf network appliances for the router/firewall software. The site has resources for selecting an appliance and configuring certain software-defined routers. Moreover, there’s plenty of information on YouTube to help you with initial installation and configuration. Of course, you can assemble your own using an x86 single-board computer or PC parts (as @Tromperie has done).