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I build something similar https://sschueller.github.io/posts/vbz-fahrgastinformation/ but with way less BOM and I keep getting asked that I should sell them. The primary reason I don't is because I don't want to support something like that for the next 10 years...
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Stream
Stream - Scalable APIs for Chat, Feeds, Moderation, & Video. Stream helps developers build engaging apps that scale to millions with performant and flexible Chat, Feeds, Moderation, and Video APIs and SDKs powered by a global edge network and enterprise-grade infrastructure.
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A Raspberry Pi Pico W is a microcontroller (no operating system) that incorporates Wifi. The way it works is you write a program that runs in a loop and talks to the GPIO ports or whatever. It's incredibly simple and it all runs from flash, so no operating system or anything else needed.
I like using TinyGo with these kind of boards so I get concurrency as well, although sadly the Pico W doesn't have Tinygo support yet. With the W versions, once you're connected to WiFi you can poll APIs and do anything else you do on the internet. No OS required!
As an example of a whole, stand-alone program, I wrote a digital clock in TinyGo. https://github.com/doctor-eval/clocky - sadly it can't (yet) connect to the internet so it's running on a pre-W Pico.
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ESP32-HUB75-MatrixPanel-DMA
An Adafruit GFX Compatible Library for the ESP32, ESP32-S2, ESP32-S3 to drive HUB75 LED matrix panels using DMA for high refresh rates. Supports panel chaining.
The ESP32 can handle a 64x64 HUB75 display pretty handily. Several of them, even. There’s a solid library out there [0] that just pumps pixels right from memory via the ESP32’s built-in DMA engine. Adafruit_GFX is the supported library for drawing primitives/text/bitmaps/etc., so you can re-use a lot of code that’s out there.
But let’s start with a simple, quick hit of dopamine: There’s a web-based installer [1] (it uses web serial, so Chrome is required) for a couple varieties of clock designed for a 64x64 HUB75 panel and an ESP32. $20 in parts from AliExpress if you already have a suitable 5V power supply.
To use that site, all you need is that aforementioned 5V power supply—4A or more recommended, 10A if you’re planning to drive a full panel of pixels on an outdoor panel at full brightness—a 64x64 HUB75 matrix panel, and an ESP32. Everything except power is run directly to the ESP32. Many panels even come with a 16-pin female IDC connector for the panel, with individual DuPont-style female connectors at the other end that you can just slip over the pins on the ESP32.
The source code for each clock (repo is linked from the web page) is a great starting point for making your own versions.
The panels, as others have mentioned, are shockingly cheap from the usual sources like eBay [2] or AliExpress (search for “HUB75 panel” or “p3 64x64”), but even those in a hurry can get a 64x64 panel for under $40 from Amazon [3].
[0]: https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-DMA
