I'd appreciate it if it was possible to long-press select some text on mobile Firefox (Android for me, but ios too) and use the offline translation feature on that selection alone.
Reading through a long page in a foreign language I somewhat understand, I found myself stumped by one sentence or two. I wish Firefox would let me to translate only those, and not force me to wait longer to translate the entire page.
This is already possible on desktop. Please consider bringing this feature to mobile as well.