With the iPad and MacBook Apple added 160 MHz support for 6E only (not on 5 GHz still, which makes sense). Did they really not do that with the new iPhone 15 Pro as well? A bit disappointing really.

2400Mbps = 300 MB (megabytes)/s x2 = 600MB/s which is pretty close to the number the OP was stating. So to get over 1GB/s you need more than 2x2, right?

I supposed that depends if you interpret GBPS as someone holding shift or someone really meaning to express network speeds in bytes and just happens to capitalize the rest too. But yeah, to get over 1 GB/s (or 8 Gbps) you'd need more than a 2x2 setup even with the massive 320 MHz channels Wi-Fi 7 is going to bring.

And you have to divide the PHY symbol rate by 4 to get the real world TCP throughout achievable.

There is some loss but you shouldn't be getting anything near 4 unless something is very wrong with your wireless environment. Even a flat half is pretty bad. In a hospital environment our managed clients (i.e. laptops, phones, wireless desktops) in the 5 GHz space would reach more near ~80% theoretical.

Both Eero and Apple only support 160 MHz channels in 6 GHz