Oh, if you have zero experience working with microcontrollers and only have worked with Arduino Uno and Arduino libraries, I very strongly suggest you get Arduino Uno or compatible boards and work with these. Even from iffy sources. Trying to start learning microcontrollers now, from scratch, would be very time-consuming and would kill your actual project.
Sure, I have worked that way in the past, promise something in 3 months then start learning how the heck I do that. And then it takes 6-9 months and the customer is not happy. In the end, it always worked out but it's a stressful situation.
Really, unless you are really experienced, the best advice is to keep using what you are comfortable with. Unless you know that Arduino libraries are available on some other MCU, and you know they work exactly (or very close to) the same, assuming this and just buying something is a huge risk. You'll learn, sure, but you'll fail to deliver the project as well.
When you are more experienced and worked with many different microcontroller families, you get better at finding the relevant things in the documentation and have seen many of the traps, so it's much faster to develop even on an unknown microcontroller. And if you have worked on 8-bit PIC or AVR before the Arduino era, that's a really good start to build on, but if you have only worked with Arduino libraries and your projects have been simple enough so that you didn't need anything else, then you have quite some road ahead. You may be able to cope with libraries of whatever MCU vendor (such as STM32 HAL) but the problem is, they are all different, they are not similar to Arduino libraries at all, and look much more complex and bloaty, compared to the simple Arduino interfaces.
Arduino sure does good job getting people motivated, but it's really like those training wheels. The next step is to remove the training wheels and keep going (this includes falling sometimes), not buying a Harley Davidson motorcycle.