How Thunderbolt Support Is Provided on latest LGA1700 Boards

[achugh]

Does anyone here knows how latest motherboards like ROG Maximus Z790 Dark Hero provide built-in Thunderbolt support?

What I mean here is that the documentation says that the 2 Thunderbolt 4 ports at the back of the board CAN support up to 40Gbps of data transfer.

I would like to understand and know how these ports are sharing or bifurcating the data pipeline. I am assuming that both these ports are connected to the Z790 chipset. This means they are really limited by the Chipset to CPU DMI bridge connection. Is there any ASUS board with an Intel Card that I can install to directly connect the Thunderbolt ports to the CPU? This way I hope to get full access to Thunderbolt 4 bandwidth.

Intel 14th Gen CPU (and for that matter 13th Gen CPUs as well) provide 4 lanes of PCIe 4.0 plus 16 lanes of PCIe 5.0. Keeping the PCIe 5.0 lanes for GPUs or Hyper Cards that ASUS has come out with (see https://www.tomshardware.com/news/asus-pcie-card-hits-512-gbps-with-four-pcie-50-ssds); how can we use these 4 x PCIe 4.0 lanes for Thunderbolt support?

My 2nd question is, for general Adobe Lightroom and Photoshop work, what kind of nVidia GPU is recommended that can potentially work with 8 lanes of PCIe 5.0 instead of all 16 lanes. This way I can use the first PCIe slot for GPU and the 2nd PCIe slot for the new Hyper M.2 Card to get very high speed storage since I would like to configure the machine with x8/x8 PCIe 5.0.

For reference, I was looking at https://www.intel.com/content/www/us/en/products/docs/chipsets/desktop-chipsets/z790-chipset-brief.h... page with the diagram showing the capabilities of Z790 Chipset along with product briefs of ASUS motherboards.