With the solid fuel tablets you can try making your own stove. I have one made from a sheet of thin steel folded into a square "U" shape and stood on its end, forming 3 vertical walls. There's a low-down cross-piece to hold the fuel, which is roughly square with two tabs sticking out that go into slots cut into the opposite two walls. The pot sits on top. It seems to work reasonably well.

I picked that shape because I have a square tin that holds a PSK. The 3 sides of the stove fit inside the left, bottom and right sides of the tin, and the cross-piece lies flat across the bottom, so it takes up very little space.

Another approach is to use one of those round alcohol stoves, eg a Trangia, and keep it inside a steel mug, and cut a round tin-can to use as a support and wind-shield and put that in the mug too, and then make a lid to go on top.

In other words, instead of reducing the space the stove takes up, find ways of packing it efficiently so no space is wasted. With solid fuel tablets you really just need a platform for the fuel and something else to hold the pot, and to protect it from wind and keep it from scorching the grass.

Incidentally, the square Esbit-style stoves come in two sizes, the larger being about 4.5" at the longest side and the smalller 3.75". I usually find the smaller is a false economy because the space inside the larger is more useful - I keep a lighter, tinder and spoon in there as well as the fuel itself.

The fuel itself also comes in many forms. I prefer the British Army rectangular waxy style. It packs more efficiently than the Esbit blister packs.