Sweat runs a normal Brainfuck program. Loops, branching, and output run as software, instantly, the way they would in any interpreter.
But +, -, >, and < don't just happen. Each one is decomposed into a chain of NAND gates — roughly 40 for an 8-bit increment, 56 for a decrement — and the operator resolves them one at a time: two bits, A and B, one button press for NAND(A,B). The machine already knows the answer. You compute it anyway.
The operator is never told which instruction they're inside of, or what cell or pointer they're touching. The output accumulates on the right, slowly, disconnected from the labor producing it — the way a factory floor is disconnected from the storefront selling what it made.
Wrong button presses aren't corrected. They're accepted as the gate's output and ripple forward into the byte being built, same as they would on a real line.