I am not willing to do surveys or anything else on my smart phone. I have a desktop and a tablet. Those two are good enough for sites like FC.
I don't begrudge anybody who makes that decision as it is a personal choice and really each person has the right to decide for him or herself what they are willing to disclose - but I have to tell you that I have been making a lot of spending money using smartphone apps. Several people have commented on different apps both here and in other threads.
Just this past weekend over the course of an hour or two I earned $50 in Amazon credit using a single app where they ask you to record short 5 minute videos of your decision making process as you shop for a specific product category in a grocery store. You often have to shop for (or evaluate) specific brands and they have several questions that you HAVE to comment on in order to qualify for payment, but most of their tasks pay anywhere from $5 to $25. On Saturday, I was able to do three $10 projects at Walmart and Meijer and one $20 project at Target. In my area, those three stores are all on the same strip within about a mile or two.
Easy money all from a smartphone! Using just that one app, I've earned almost $1,200 in Amazon credit since the summer of 2017.