That's EOL now, so nowadays I'd look to ARM e.g. https://radxa.com/products/network-computer/e52c
For wireless AP i have an Mediatek MT7621 device, they are very well supported and provide proper wifi throuput
My setup is honestly simple enough that a write-up would not benefit many. My Unbound setup to block many malicious sites is also fairly well documented by others. The null routing of commonly used DoH servers is straight forward. My Chrony setup would just annoy people as I only use stratum-1 servers and the options would just look like cargo-culting to some.
About the only thing not commonly discussed is the combination of thc_cake and some sysctl options to keep buffer bloat low but OpenWRT has their own take on that topic already.