Do SSDs in multi-bay enclosures share Thunderbolt 4 bandwidth?

After doing more research, this is how I look at this question now:

There are different combinations of three interfaces:

1. The downstream interface of the enclosure to its SSD
2. The upstream interface of the enclosure for the host to connect to
3. The interace of the host port

The combination of these connections results in basically 5 speed categories:

To let multiple SSDs connect at up to the full bandwidth, you could connect them to a Thunderbolt 4 dock. When multiple Thunderbolt 3 PCIe enclosures simutaneously use PCIe, then the bandwidth of 4 lanes of PCIe 3 are shared across all the devices.

That's what I want.

From a practical, human-centered point of view, I would prefer one enclosure that can achieve the same, rather than daisy-chaining.

Here is an idea: If my goal is to create a setup that makes all four PCIe lanes available for data transfer in order to support the maximum speed of an NVMe SSD, why not use it with a x16 PCIe card like the Sabrent EC-PCIE in an enclosure that has a x16 physical slot?

In the meantine, I have found:

The Thunderbolt port provides 4 PCIe lanes. Therefore, an enlosure for four SSDs will only allocate one lane for each. To use the full Thunderbolt bandwidth, the SSDs have to be put in a RAID configuration to use the 4 lanes simultaneously. An enclosure for 2 SSDs might allocate one or two lanes - something to check before buying.

To check whether there is a Thunderbolt bus for each of the 4 ports, I could use system information later, when a device is connected. (On the late 2017 iMac Pro, two Thunderbolt 3 ports share one Thunderbolt bus, per this 9to5Mac review of the OWC Thunderblade enclosure).