The main selling point of the 5700G is that it has integrated graphics. If you plan on using a discrete graphics card like the 7800XT then you don't need an APU, and in fact can get better performance out of an "X" series processor.
For example:
The 5700G is Cezanne core which has reduced L3 cache (16MB) and only PCIE 3.0 support.
The 5700X is Vermeer core which has increased L3 cache (32MB) and has PCIE 4.0 support.
Ryzen R7 5700X | B550 Gaming X | 2x16GB G.Skill 3600 | Radeon RX 7900XT
Ryzen R7 5700G | B550 Gaming X | 2x8GB G.Skill 4000 | Radeon Vega 8 IGP
Ryzen R5 5600 | B550 Gaming Edge | 4x8GB G.Skill 3600 | Radeon RX 6800XT