Is Arduino outdated?

I wouldn’t say so. I’ve used the Nano for a number of projects. Chinese legal copies are available for less than £2. The processor is fine for many real world applications, as long as you realise its limits.

I made a darts marker, and Just for the hell of it, I added an IR sensor so that it could be operated by a TV remote, with a learning facility to adapt to any remote, storing the codes in EPROM.

The marker used about half of the Nano’s program memory and half of the RAM (you need to leave a fair bit of spare RAM for the stack), plus a few hundred bytes of EPROM. Not bad for a £2 chip.