Just as with the launch of 3G & 4G services, 5G is in relative infancy compared with the comprehensive & mature 4G network - it's no surprise to find 4G coverage exceeding that of 5G except in locations where the two services are using comparable bands from the same serving site.
No network guarantees 100% indoor coverage nationally, WiFi-calling is an excellent mitigation for poor indoor coverage whenever it occurs. For every location where EE is poor & VF is good, there will be others where the opposite is the case. For that reason, if you are considering a change of network, I strongly recommend the use of PAYG SIMs by means of survey. A real-world test of different operators is always better than relying on computer predictions.
For what it's worth, I know of many rural locations that have better coverage than urban areas - coverage is largely dictated by site placement & band usage, rather than which RAT you're connected to.
