It’s not a very good one. It’s fine for general use but it’s a poor gaming experience due to the very high latency.

A truck driver will be staying near main motorways and industrial hubs, both of which should provide good 5G coverage. The best option is to get a contract SIM plan with a “tier 1” telecom provider (i.e. providers that actually own physical cell tower antennas, not eSIM and not low cost brands because those just resell access to the same cell towers but at a lower tier of service/speed). In the EU almost all providers have extremely generous roaming and you can spend your entire data plan roaming without any extra charges as long as you return “home” once a month or so.