First of all, I want to thank a guy named Drew on YouTube for putting together a video on how to do this and his help.
YouTube Video: (3-way Shelly1 Fire Place Control) (https://youtu.be/C4Vs1qELse0)
I bought Shelly1 from an eBay seller who used RavenCore to light Shelly's flash so it could be used in HK.
HomekitBG provided me with a (schematic) (https://imgur.com/a/d3NegkW) how to connect this. The only thing I changed is that I used 12 volts DC instead of 24 volts. You will see two schemes, please note that I only followed the one above.
EBay listing for Shelly1 with HomeKit: (Shelly1 with HomeKit) (https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F173850133408 )
I used a 110/120 Volt to 12 Volt DC AC adapter that I found at the $ 1 savings store after I drove to Lowe's to find out he wasn't wearing it. You can buy this news from Amazon (https://www.amazon.com/R-Tech-UL-Listed-Switching-Supply-Adapter/dp/B00FEOB4EI). I cut the cylindrical plug at the end of the cable and connected them to Shelly to give it power. You will connect the negative cable to the "N" port. The negative side is usually marked with either a white tape or another mark. The positive will be connected to the "L" port. This port will be split with a wire from a mute wall switch if you want to have a 3-way configuration.
We then connected the brown wires, which supply the 3V Milliamp power to the gas valve, to the "I and O" connections. This is where Shelly controls the contact.
To gain 3-way control with your physical wall switch, you will connect one wire to the "SW" port and the other wire from the switch to the "L" port. For confirmation, the "L" port is shared with the positive cable from the DC adapter.
I hope you found this useful. I'm going to use these shelly1s to control my pool equipment and water features.