Singleplayer supported?

[NaBrHCl]

Is it possible to enter a save in singleplayer mode, without setting up any server locally?

[M0on9]

https://minecraft.wiki/w/Java_Edition_1.3.1#General_2
The minecraft client runs an internal server, which (I'm asusming) would be out of scope for this project.
Running PumpkinMC on localhost would work for 100% rust "singleplayer" if you don't mind not having the worlds menu.