Segmentation and checksumming are very common, with the segmentation often called TSO (Transmission Segmentation Offload) for send and LRO (Large Receive Offload) for receive. However, usually when referred to as a TCP Offload Engine (ToE) it does mean pretty much the whole protocol, as least a functional subset of it anyway. Windows and FreeBSD support ToE with some NICs. Linux has rejected full ToE in mainline for a number of pretty solid reasons:
https://wiki.linuxfoundation.org/networking/toe