I was considering making tetris but with dice as well, so it's cool to see someone attacking this idea.
I think it's a cool concept, though definitely needs some more design consideration.
I think the key to any tetris-like game is sustainability. Can the player, if skilled enough, maintain the stack and keep clearing lines? The way the game currently is set up, you only clear the equation you've made horizontally, meaning that everything you can't make into an equation is left as unclearable junk unless you manage to align it after a clear.
You said you will add vertical and diagonal equations, and that will definitely help, but i would suggest thinking of other ways to allow the player to clean their stack. perhaps an equation also clears the blocks next to them, so you need to use your junk as spacers so you don't eat other equations. or perhaps you clear the whole line which has an equation, maybe a certain amount of blocks taking the complexity of equations to account.
definitely lots to explore there :)
Good job on the jam!