Rome Travel Advice

Hey everyone!
I am going to be travelling through Rome’s FCO and was considering staying in Rome for night or so just to see the city, since im already there. I was reading through some posts on whether it dangerous or not, my main concern is going through Termini to my hotel (say 15min max) with my carry on suitcase, I will def have my documents in another purse attached to me or smth, but is there a great chance of my suitcase being stolen? (I am supposed to go through Termini twice, at 12.55 and approximately 18.30) I am also from a tourist attraction city so pickpocketers are not as scary, my main concern is those stories of people just openly grabbing phones/bags and running away. Another question is mobile connection, roaming is hella expensive and getting sim for just one day seems a bit useless.. how are the things with Open City Wifi in Rome? Does it exist? Or should i consider a sim card?
Thank you all! It’s my first time in major European city so any advice matters!