Not great by modern standards... The standard ESP32 supports 802.11n, but only 2.4 GHz (not 5). So theoretical rates maybe up to 40-50 Mbps. In tests that I have seen people do on ESP32 they have reported practical speeds of 5-10 Mbps. Which is basically just in the typical range for Full HD video.
The ESP32-C6 has WiFi 6 support and 5 GHz, so theoretically that can be order of magnitude faster. But it might have completely different hardware and require separate reverse engineering. And practical speeds will still be limited compared to dedicated WiFi hardware.
I know its not exactly what you mean but here is video download, decoding, and video signal generation on a bare esp32 (no Graphical chip) : https://github.com/rossumur/espflix
It’s a dual core MCU that runs at around 240MHz.
One of the main limitation tends to be to be around pushing pixels to the screen - most displays are serial (SPI) based which tops out at 80Mhz.
The other limitation is a lack of hardware video decoding. Some of the latest ESP32 chips are RISCV based and have SIMD instructions which can improve decode performance.
But if you pick an easy to decode codec (MJPEG) is popular. The you can get decent performance with the size of displays available.
I understood the parent coment as wanting to build a WIFI card, i. e. the ESP32 connects to the WIFI and transfers the data to a connected computer over PCIe or so. The ESP32 would have to do no decoding of the payload, only transfer the packets to the PC.
The ESP32-C6 has WiFi 6 support and 5 GHz, so theoretically that can be order of magnitude faster. But it might have completely different hardware and require separate reverse engineering. And practical speeds will still be limited compared to dedicated WiFi hardware.