Can someone explain to me what I'm looking at it?
10BASE-T = 10 Mbit/s Ethernet. 10G/2.5G/1G/100 Ethernet are all backwards compatible so 10BASE-T is the slowest/simplest Ethernet standard that you can implement today and just plug into just about anything.
This is transmit only, so it's pretty much limited to broadcasts (can't do ARP). That's good enough for e.g. sensors.
I need more context.
Is a micro-controller able to broadcast through an ethernet port something remarkable?
Obviously this upvoted enough that it's causing a buzz, but I'm not an embedded guy and don't really understand why.
Many microcontrollers, especially higher-end ones, have built-in dedicated hardware, called peripherals[1], to handle complex and/or high-speed interfaces like Ethernet.
The Pico does not have an Ethernet peripheral, so this project relies on bit-banging[2], a brute-force approach to IO. However, the Pico does have the PIO[3], which is a general-purpose IO peripheral, so it's not pure bit-banging in the traditional sense.
While it's cute, it's not super remarkable. People have done bit-banged HDMI[4] on the Pico for example. However, Ethernet access can be very useful in a Pico project.
[1]: https://electronicguidebook.com/what-are-microcontroller-per...
[2]: https://en.wikipedia.org/wiki/Bit_banging
[3]: https://hackspace.raspberrypi.com/articles/what-is-programma...