"Wi-Fi" is a trademark referring to the 802.11 family and has layer2 definitionally baked in.
If you want to roll your own layer2, you specifically do NOT want WiFi or 802.11 family chips.
You may have luck finding what you're looking for by searching for "single chip transceiver."
FWIW this seems like an example of the XY Problem, where you're asking about your attempted solution rather than your actual problem. Perhaps you would consider backing up and sharing what you're trying to accomplish with this solution?