Craig,
I haven’t used a Wemos D1, but it should run ST_Anything without too much effort. I believe others have successfully done so already. Controlling the GPIO pins on a microcontroller is what ST_Anything does best! You should be able to simply edit just the Arduino sketch to support the devices you want to attach to the Wemos D1 and be good to go! The ST_Anything SmartThings Groovy Device Handler code is now generic so you really just need to add my repository to your ST IDE account and install/publish the device handlers. Very little code for you to write.
Take a look at the main ST_Anything project discussion below, as well as read through my GitHub ReadMe file to get started. Just be sure to follow the instructions for the NodeMCU ESP8266 as that is the closest device to a Wemos D1 (i.e. the same micocontroller.) In the Arduino IDE though, be sure to select the Wemos D1 as your board type.