The RP2040 boards are not an Arduino though (albeit there do exist tools to utilise the RP2040 from the Arduino IDE and etc.) and the PIO module is much more than just another bank of GPIO. It totally can drive HDMI (well DVI) - GitHub - Wren6991/PicoDVI: Bitbanged DVI on the RP2040 Microcontroller[^] though the more usual way to get video out of one is to drive VGA since the dot clock is a lot slower: GitHub - raspberrypi/pico-playground[^] see the "scanvideo" section there.

I missed the start of this, but I sense from the wording this may be part of an ongoing "question"... How much processing oomph is needed? If it is not too much, is the RP2040 chip enough? (As featured in the Raspberry Pico and various Adafruit boards, etc.) It has a couple of Arm cores, some RAM, some Flash and a bank of PIO - this last bit is the interesting bit: in my head it's like a little bit of FPGA, but in any case you can program it (in a C-like language) to off-load intensive operations from the CPUs. The crux here being that folks have programmed the PIO to drive HDMI displays and so forth... TBH, I've never used the PIO to drive HDMI, but I have used the RP2040 in a number of projects and it's been surprisingly good. I've only ever used the C-SDK, but there's support for various embedded-Python dialects too, they tell me. The C-SDK also includes ports of LWIP (for Ethernet stuff) and TinyUSB (for USB host or device stuff) amongst other libs. I've not used LWIP on this (have used it on other boards in the past; worked well but its API is quite unlike BSD-sockets!) but I have used the TinyUSB a fair bit and was surprised by how well it worked (mainly because I found, and still find, the API confusing and was surprised when my prototype actually worked at all!) Also, cheap as chips* (*or other item idiomatically identified as low in cost by your respective cultures.)

Back in the day, I used "Synergy" for that. It worked then, but have not used it in years... AFAIK it still exists in a free version though.