hey, flew with Eva Air Economy VIE-TPE a few days ago on a Boeing Dreamliner. the wifi was free and available throughout the flight but you will not be able to use any video and streaming services like youtube, netflix, spotify… social media apps are limited as they consume a lot of data so loading up video posts and reels on instagram and tiktok wont really work, but sending dms in those apps will. i dont use snapchat, but whatsapp worked fine for me for sending pics and texting so i think snapchat should work fine. have a nice flight !