Regarding the SDR, the Pico can act as a USB host (honestly a huge win as you can plug in a keyboard/mouse). But it’s not able to run at USB 2 speed. There’s no software for it and the CPU probably isn’t powerful enough. So in that case a Linux machine is completely justified. I tell people to reach for a Pi when they need both Linux and GPIO. But if you just need GPIO you should really save the money (and get major wins in simplicity) with the Pico.
I get the familiar angle of using a Pi Zero. But don’t be intimidated by the Pico. Especially these days with the help of an LLM, you’re not slowed down too much. The version of Python they run feels very familiar. The tooling is good. They’re awesome!
Oh, these days I still suck at code. And with the bot, I can hammer out a project for ESP32 or a Pi Pico in no time. (I didn't even put together the dev environment for that. I had the bot do it.)
And because I still suck at code: If I want to create something myself, then I still get to do that with a Linux box using unix methods.
That all said: I do enjoy working with RP2040 PIO assembler sometimes. The combination of its severe limitations and robustly resolute timing makes it both approachable, and fun. :)
Anyway, I think all methods are OK. There's no reason to judge them. (I think it's also OK to just use a computer to read Facebook, or as a porn machine, or to become an Amish leatherworker and leave all of this digital nonsense behind.)
The PIO is super cool. I haven't had a good use case for it yet but will enjoy messing with it once I do.
Party I am petitioning for passersby who might be wincing at the new prices for Pi 5s etc. for starter electronics/programming projects when they could save a ton of money with a Pico. I have to assume that a huge chunk of Pi 5 purchases from consumers end up with the computer either stuck in a drawer, having been used for a couple days, or running a workload they are completely overpowered for. Every time I see the new prices I wonder how much lower they would be if the consumers were better informed and demand was more appropriately redirected.
To give a specific example of a misused Pi, I've seen an RFID access system made by a hobbyist (low stakes, no need for professional/commercial solutions) running on a Pi 3. When the system glitches (another matter entirely - messy code) and needs to be rebooted you need to wait a minute or two for Linux to start up. I'm planning to replace this system with a Pico 2W. All it needs to do is handle a couple of buttons, a small LCD screen, and an RFID reader. We can handle all of that and a WiFi-accessible web admin interface using a microcontroller. Not only is it wasteful (for whatever that's worth) to have a quad core CPU, 1GB of RAM, and a whole Linux OS to perform such a trivial task. It's also leading to issues with complexity and performance.