Permanent solution for controlling WS2812b via usb

Hi,
this might be a stupid or easy to answer question, but i didn't find anything to solve my problem.

At the moment I'm using an arduino(uno) and Glediator(/Jinx) to control an LED Matrix of ws2812b's.
But i have to upload the Arduino sketch every time after power loss. (which is normal obviously, but i'd like no avoid that).

Is there any good solution/ way to flash a sketch to an arduino permanently/ or do you know what microcontroller to use?
The USB functionality is important. People usually suggest Attiny chips, but they don't seem to provide what i need.

Thanks in advance!

I've never had a '328P lose its programming after downloading in 6+ years of developing. We do see this reported here occasionally, I don't recall a good explanation as to why it happens or what it takes to solve it.