I don't have that much experience (don't really have many use cases for FPGAs personally tbh) but: Icestorm is for iCE40, Trellis is for ECP5 (which comes in v

I don't have that much experience (don't really have many use cases for FPGAs personally tbh) but: Icestorm is for iCE40, Trellis is for ECP5 (which comes in variants up to 85k LUTs); the flow is simple enough to do manually but there are things that make it one-click. This tutorial series https://youtube.com/playlist?list=PLEBQazB0HUyT1WmMONxRZn9NmQ_9CIKhb https://youtube.com/playlist?list=PLEBQazB0HUyT1WmMONxRZn9Nm... uses one. As for handling really big designs, I don't know.