So, it's exceptionally easy to download Orbot, and Monerujo and have it so Monerujo connects to a Tor Node via the Orbot VPN service. This allows you to send transactions on the Tor network. You can read about it here: https://www.reddit.com/r/Monero/comments/7ccstc/small_psa_you_can_connect_monerujo_through_orbot/
Thing that worries me is if this is good enough for a darknet market purchase? I get it is probably less than ideal - but considering how private and anonymous Monero is to begin with, and the fact that Orbot + Monerujo would be concealing your IP address and ultimately be put into the blockchain on the hidden service monero full node... it should be good enough, right?
Thinking that the purchase can be made on TAILS but then could send payment via phone?
Seems like an easy/secure way to use Monero but I'm not 100% sure.
Mobiles are designed to harvest your data. I use a laptop that's strictly for DNM. This laptop has never seen the clear web. Also I only connect to DNMs using a public wifi hot spot so my ISP doesn't flag any activity. Safety is everything.