Most trips start in Helsinki, and this is where your phone works hardest. You will pull up maps to find the Market Square, check tram times, book a table in Punavuori, or scan a code at the Suomenlinna ferry. DNA gives strong 4G and 5G across the whole capital area, so video calls and streaming load fast.
Helsinki Airport has free fast Wi Fi, which is the perfect moment to switch your eSIM on. From there the signal stays solid through Espoo, Vantaa, and down the coast to Porvoo and Turku. If your trip is mostly city days, the 3 GB for 15 days plan at $2.10 is plenty for maps, chat, and light browsing.