I am the dev for Repurposed Structures and while I had done a compat datapack between Etched and Repurposed Structures before, I was wondering if you would be willing to accept a 1.21.1 PR to have this compat built into Etched directly by shipping specific json files.
https://www.curseforge.com/minecraft/texture-packs/repurposed-structures-etched-datapack-compat

The only code needed (and is optional) is registering a config value into my custom registry to turn on/off the RS compat by config. RS will handle the injection by checking for the special json. You don't even need to build against RS to add to the optional conditions registry.

This way Etched has compat out of the box for Repurposed Structures for 1.21.1+.

Lmk if you are interested in me making a PR to your project or if this compat should stay as a separate datapack/mod project.

If you want to see an example of what this compat would look like, check out this PR to another mod: BluSunrize/ImmersiveEngineering#6139

Also, let me know if you want me to add you to the 1.20.1 compat datapack project and give you a cut of cursepoints/modrinth revenue.
https://www.curseforge.com/minecraft/texture-packs/repurposed-structures-etched-datapack-compat

If so, let me know what % you want.