I recenly complete a 25 day trip through Germany, Austria, and Czech Republic. Before going I considered using my AT&T plan which gives me data for $10 per day on any day I accessed the feature (used this in February) or getting an eSim with a data plan. Based upon my average US data usage I decided not to get an eSim as I often us significanly more data than provided for in the lower cost plans.
My solution? WiFi only.
It worked just fine for me. Every hotel, most restaurants, most museums and other tourist sites, some grocery stores (!), and most subways and subway stations have WiFi. I could check messages and access online content during the day or at my hotel in the morning/evening. iPhone GPS was always on, so I could use WiFi to download detailed Google Maps for my day and then check my progress while offline from WiFi. If I got lost or needed some information, I just wandered up to the window outside the nearest US fast food chain or Starbucks.
Real-time communication back home was via FaceTime from a hotel or restaurant. I am retired so no one "needs" to reach me. Just me keeping in touch with family and friends at night. I also downloaded Google Translate, transit apps for both trains and metros, museum apps, Rick's audios, etc. and used them offline. When traveling I post on Istragram, no problem finding hotspots to keep the world informed of my travel.
Over the course of just over three weeks there were only a couple of times when I considered using AT&T for that day. Next time I will spend the $10 on those days. For this past trip I wanted to see what was possible.