Thanks for the kind words. I like teaching and helping, and I'd thus typically be happy to consider doing a tutorial. However, OneMarcFifty (https://youtube.com/@onemarcfifty, https://www.onemarcfifty.com) already happens to have a nice tutorial on setting up VLANs in OpenWRT: https://youtu.be/qeuZqRqH-ug. The tutorial gives clear instructions, importantly differentiating different ways to establish VLANs, including use of bridge VLAN filtering with DSA (distributed switch architecture) introduced in OpenWRT 21. I'd first point folks in that direction before doing my own tutorial. Folks may have to generalize a bit or discern where things do or don't apply based on their own topology (e.g., using one or more GL.iNet product(s) for the entire network vs. using a GL.iNet product just for the routing capabilities with the network topology also including, say, a managed switch and access points from another vendor for WiFi), but the above tutorial really hits the key points (and also points people toward related resources where relevant, such as configuring firewall rules).
I hope this helps!