Note that many European countries have already got rid of their 3G networks completely [0]. So it's either "you have 4G/5G" or "the internet is pretty much unusable", nothing in between.

As someone living in a European country with no 3G network, my experience with mobile data is that when my phone fails to find a 4G signal and switches to 2G (pretty much only happens in remote areas, thankfully), I can as well send my packets using a pigeon carrier, they're going to arrive to the destination sooner.

[0] https://en.wikipedia.org/wiki/3G#Phase-out