charge zephyrus g14 laptop to 100% or 80%?

I use my laptop for school and occasionally gaming but a lot of times as a desktop plugged into a monitor and peripherals. I am sick of my laptop being at 80 percent when I go out, because I charge it to max 80% when using it as a desktop. Is it really that worth it to never charge it to 100%. I was charging it to 100% right when I got the laptop so the battery is already at 89% health. Also is the battery replaceable?