ChaCha20 satisfies your conditions.

The only disadvantage of ChaCha20 vs. Speck is a bigger state, you need 128 bytes for it (64 bytes of state + 64 bytes for the intermediate computations), but that is not likely to be a problem, except in the smallest microcontrollers.

The bigger state of ChaCha20 is determined by higher security requirements. The advantage of ChaCha20 is that it is supported by standard protocols, e.g. TLS 1.3 and SSH.

The standard protocols mentioned above include ChaCha20 precisely for the case of communication with smaller or older CPUs, which do not have hardware AES support.