[CHAT] Stitching Apps?

I’m working on a huge piece and I’ve never used an app for stitching. How do these work to count stitches? How do these work for multi-page .pdf patterns? Do I need a tablet or is this something easily done on a phone? All experience appreciated.

I have a goal to finish this piece in time for the county fair in September so tracking my pace to see if this is a reasonable goal would be SO helpful.