Thunderbolt™ 3 & 4 Explained:

Thunderbolt 4 is compatible with plenty of connections or interfaces including:

DisplayPort
PCle
USB4
It’s even backwards compatible with previous versions of Thunderbolt and connects via USB Type-C
When it comes to speed, Thunderbolt 4 ports have 40Gbps bandwidth. However, Thunderbolt 4 stands out by increasing Thunderbolt 3’s minimum PCIe data requirements from 16Gbps to 32Gbps. That means more room for higher transfer rates and better performance.

For external devices that use PCIe, Thunderbolt 4 will work like a charm.

Games can be transferred and stored onto an external drive and be played from there, rather than having to transfer the files to the system instead
Last and certainly not least, especially for laptop enthusiasts, Thunderbolt 4 is capable of charging various devices and you won’t need a separate power supply to charge your device.