After more experimentation, experience, and research, I have found...
  • Thunderbolt 2, 3, & 4 will daisy-chain up to six links, Older displays that are using DP 1.1a or earlier must be located at the end of a Thunderbolt device chain.
  • Native displays and Thunderbolt devices can be anywhere along the line. (Apple states that up to six daisy-chained peripherals are supported per Thunderbolt port and that the display should come at the end of the chain, if it does not support daisy chaining.
  • Thunderbolt 2 uses the MDP connector and has a maximum speed of 20Gb/s
  • Thunderbolt 3 uses the USB type C connector, requires an activecable[/i] connections that can support up to 20 or 40Gb/s speeds. (Apple has always specified the maximum data rate in its computers and devices.)
  • Thunderbolt 4 raises the minimum bandwidth to 32Gb/s (but retains the maximum 40Gb/s), adds support for dual 4K displays, DMA (Direct Memory Access) protection, adds support for distributed signaling in addition to daisy-chaining, and support for the USB 4 standards.
  • M1 Macs have two Thunderbolt 4 ports and both daisy-chain and distribute, but will only support one 4k or 6k Thunderbolt monitor, but have been demonstrated to daisy-chain up to six HDMI monitors. (I am running one Thunderbolt 4K monitor and one "Full HD" HDMI monitor via the M1's HDMI port and a variety of Thunderbolt 3 SSDs via an OWC Thunderbolt 4 hub.) I had some issues with the initial setup, but as far as I can tell the problem was the result of mixing USB, 20 Gb/s TB3, and 40Gb/s TB3 cables. Replacing the USB and 20Gb/s TB3 cables, with certified 40GB/S cables solved any problems.
  • So far I have found only one certified TB4 cable and it came with the OWC TB4 Hub, but as of today, OWC does not offer that cable as a stand-alone item.

CONTINUING ISSUES
  1. Big Sur moves kernel extensions from the system area to the user area which theoretically should make the installations easier. However after any installation of a kext the Extensions cache has to be "rebuilt" (a process initiated in System Preferences > Security & Privacy > General requiring an administrative user's authorization and password), followed by a reboot of the system. I have two such kernel extensions:
    1. one of which is not compatible with Apple Silicon 😱 However, IMHO, the Big Sur developers deserve kudos for handling this situation. The system will make three attempts at installing the kernel extension then isolate it and continue the boot without the offending kext and with a full explanation of what has transpired.
    2. The other kernel extension works well, but has to be re-installed -- like every other time the system is rebooted 🤷‍♂️
  2. I have elected to FileVault my boot drive so logons require a two step process, Step one at the prompt, enter the password for the file system, step to enter the logon password. (Both are the same password and this may be an issue between the headlights, and not in the system design.)
  3. The past two mornings I have come in to find my system has rebooted, but so far no clear indication of a cause.
  4. A couple of favorite pinball games from my iPhone/iPad don't play nice on my M1 mac 😢

Other than that my system is running fast and clean. I am genuinely pleased. 🙆‍♂️

Last edited by joemikeb; 12/02/20 10:54 PM. Reason: better wording
If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein