Some mods target the Mono version of the game, which is available by opting into the Steam beta branch "alternate"

SwapperPlugin
Allows seamless swapping between the il2cpp and mono backends. Can be used to install the mono and Il2Cpp version of a mod seamlessly
By the_croods
This mod requires the following mods to function

LavaGang-MelonLoader
The World's First Universal Mod Loader for Unity Games compatible with both Il2Cpp and Mono
Preferred version: 0.7.0README
Swapper plugin
You don't need this unless you're actively developing mods, and want to use it as a dependency.
How it works
The plugin will search through your dll for the references and if it uses any or too many Il2Cpp references it will disable it if its the mono branch and vice versa. including "Mono" or "Il2Cpp" will tell the plugin to use that backend rather than finding one.
How does this help me?
Instead of managing two manifests and packages on thunderstore, you can upload one package with both dlls and use this as a dependency. then it will do the rest, allowing the user to play freely on either backend!