There are two major distributions aimed at more than one board, they're Armbian and DietPI, I would suggest reading through their forums because of the good number of people familiar with different boards, so those might likely be the best places to ask if task X is better accomplished by board A or B etc. . Sometimes however boards are similar to each other for employing the same SoC, so it's not rare finding an image that boots successfully both a board from one vendor and a TV Box from another vendor. There are many ready images for tested hardware, but users are encouraged to rebuild the images and make more test to unknown hardware then report findings.

https://www.armbian.com/

https://dietpi.com/ (warning: puke inducing site colors! :-)

What is puke inducing there? The green?

I'd call that color scheme Liquorice-Absinthmeister :-)

> What is puke inducing there? The green?

Yes, I find it extremely uncomfortable to look at; literally a punch in the eye.