I guess you're talking about storage size and not RAM, so you should check out openwrt. There are still a lot of micro router which are still 4MB rom / 64 MB ra

I guess you're talking about storage size and not RAM, so you should check out openwrt. There are still a lot of micro router which are still 4MB rom / 64 MB ram. I compiled and run the 19.06 release (with a 4.19 kernel) on one of this target, a WR702N, last week actually :) the kernel itself is about 1MB.