According to the specs, it has 1kB of ram. You're going to need to be quite clever to implement a working TCP-IP stack and an HTTP server in that.

An RSA key is 4kB by itself, so TLS is out of the picture.

I was also going to suggest that... But I imagine that the Ethernet port or antennae wire (and necessary battery to power antennae) would dwarf the size of that MCU. But thinking again, I suppose if the rules permit the MCU to be directly wired to the Ethernet cable, then could bitbang an early Ethernet standard with this MCU's pins...

If you're going to use an Ethernet jack anyway, you might as well use one that has an ARM SoC already built in and runs Linux:

https://www.digikey.at/en/product-highlight/d/digi-intl/digi...

“Obsolete and no longer manufactured.” :-(

I'd do a serial connection using the UART. Serial is a perfectly valid transport.