First of all, it feels unbelievably freeing to run desktop GNU/Linux on my phone and benefit from the full command line (e.g., ssh and sshfs on the go are extremely helpful) and desktop Firefox, without stupid limitations of "ordinary" smartphones.
I tried to use it as a laptop. It works fine for non-heavy tasks, but not sufficiently secure for me (I prefer Qubes OS). It is very helpful for doing some configuration though. See also: https://forums.puri.sm/t/anyone-using-the-l5-as-their-main-c...
I get maybe 3-4 hours of heavy browsing. Usually, when I'm using the phone a lot, it lasts half a day. Also, the background apps are not frozen like on Android/iOS and can drain the battery very quickly if you don't close them. The good news is that you can replace the battery without tools and instantly get 100% charge again.
It can charge in about three hours with the original charger, but I often use other chargers, which are slower (e.g., it can take 6 hours or more during the night). See also: https://forums.puri.sm/t/usb-dcp-5v-1-5a-protocol-and-librem...
I didn't try steam link. I tried to install Mobian. It works but the functionality lags (https://news.ycombinator.com/item?id=39155229) behind the default PureOS, which I use. The software is still under heavy development and the phone is still getting longer battery life and smoother UI.
See also: https://forums.puri.sm/t/librem-5-daily-driven-in-profession..., https://forums.puri.sm/t/librem-5-daily-driven-in-profession....