What are the alternatives for aspiring tinkerers now?

My wife (cybernetics engineer) and I are buying a 3D printer and planned getting an Arduino as an entry point. What should we do instead? What are the best communities and resources?

ESP32.

I'm using ESP32 with platformio which has a dedicated community https://community.platformio.org/tag/espressif32

I've used devkit from M5stack, waveshare and adafruit.

(M5Stack has a full line of products for tinkering with many sensors & controllers)

You can also find many cheaper no-brand devkit anywhere but quality & docs can be unreliable.

ESP32 - quite a range of dev boards and places like Seeed and Adafruit have a nice selection of accessories. Adafruit develops CircuitPython which is IMO the lowest barrier to entry for programming MCUs. Adafruit even has CircuitPython sketches on their site for how to interface with the components they sell.

Rust on ESP32 is still a bit early - the HAL crate is still pretty unstable, but the toolchain is quite nice and I'm able to be productive enough that I never reach for C or C++.

I first got into Raspberry Pi Picos, but I've also been experimenting with Esp32's and some of the nRF chips. I mostly do CircuitPython on them but Arduino is a supported platform on those I believe.

Everyone I know who is into tinkering with microcontrollers moved onto ESP32 a long time ago now. I actually thought this headline was going to link to an article about ESP32's popularity. VSCode with the PlatformIO extension has been great for me when working with them:

https://platformio.org/

The feather series of boards from Adafruit + Curcuit/Micropython works really well if you just want to make stuff happen instead of tuning a toolchain and, like, setting up clocks with asm.

STM32 boards and PlatformIO.

ESP32 is quite popular (as seen by other suggestions) but I find the quality of Espressif, hardware/software/support, is widely varied.

FWIW PlatformIO works with Arduino and ESP32 (and will give you a better experience in so many ways)