One option is to help out various open source projects. That gives you an endless supply of options, languages and applications. You, the project and its users all benefit.

A very recent university graduate joined our company many years ago. He was quite the C++ wizard, whereas we were slowly migrating from VAX Pascal to C++. No one could understand the code he wrote as he was using all kinds of jiggery pokery without comments. We had to ask him to simplify and comment his code! 😁

That doesn’t say much about us at the time!!

Of those options, VueJs over Lia but your Java skills should transfer over to C# if you can educate yourself in that and dot Net.

Damn, I didn’t know about this. I was about to install it this weekend to check it out.

Are there any alternatives (excluding NextCloud as I don’t need it’s 1000 features) that provide mobile apps?