I was going to point this out too, but I'm frankly not sure how well the opensource toolchains actually work on these chips. I spent a number of hours a year or two back trying to figure out how to talk to the high speed serdes, and failed miserably.
But for the kinds of use cases one gets out of an ICE40, it seems the ECP5 devices are going to be pretty solid choices with the open source tool chains. Ex, lots more LUTs talking to slow devices/GPIO pins.
It seems to work well as far as I can tell, but my ECP5 unfortunately does not have the serdes. I wanted to stick to the 256 caBGA package to keep the board simple, but there is no variant with serdes... The PLLs, block ram, and other IO work fine (have not tried the DDR and gearbox blocks yet).
But for the kinds of use cases one gets out of an ICE40, it seems the ECP5 devices are going to be pretty solid choices with the open source tool chains. Ex, lots more LUTs talking to slow devices/GPIO pins.