Will not start the fuel pump was not getting power?

Before you go replacing anything yet. When you unplugged the Immobilizer and ECM, then checked for continuity from the Immobilizer connector pin 2 and the ECM connector E pin 27, it's a red/blue wire you had no continuity? If you read OL on your meter when checking the resistance between these two pins, then there is an open circuit between the Immobilizer and ECM. You don't need to replace modules for an open wire. Replacing modules is the last thing you want to do, always verify your test results first, what if you go replace those modules, reprogram everything, along with new keys and the same issues still exists. This is the test where you need to have a resistance reading (continuity). Technically less than 5 ohms. If this circuit is open, more than likely there are other wires damaged as well.

No there is an open circuit, a broken wire. You're checking on the red wire with a blue stripe, correct?

So in between the Immobilizer and ECM is this junction connector C406, that's where you need to go next, check continuity from the Immobilizer connector pin 2 to C406, it's still going to be the same color wire going in and coming out of the connector. Check both. Let me see if there's any procedure for removing the knee panel there below that vent, in some cases there is an air bag located there.

If the battery has been disconnected for a while already then, you're okay, I don't see any airbag in that location, but disconnecting the battery and letting the system discharge only takes about 3-5 minutes. But C406 looks to just be a junction bus bar type connector, where it simply connects the two wires when the two connectors are plugged in. If you have any water leaks it looks to be a location where water intrusion might be an issue, but you'll have to check it. You should have continuity from one red/blue wire D2 to the other E2. And also check for continuity from the Immobilizer connector to C406 as well. We're basically tracing the circuit back to locate the open.

I just realized the Data Link connector "DIAG" wire runs through C406 as well, I'm wondering if that's why there are issues with the scan tool as well.

The 10.86volts on pin 7 might be correct, it could be an 11volt signal, or the multimeter is not fast enough to read the signal so it's just giving an average of voltage its reading, since pin 7 looks to be the K-Line which would be scan tool communications.
You weren't able to manually put the VIN in either?

What scan tool are you using? It should have read the VIN pretty quick and give you access to scan at least the ECM if it's a basic OBD2 scan tool.

Did you check pin 16 of the data link connector for power yet? It's the pin that powers up a scan tool.

You obviously have a wiring issue, go check C406 for any issues. Forget the scan tool until you find the wiring issue between the Immobilizer and ECM.

Okay, I had to go back and see where you are at by this point, so with the meter set on Ohms (resistance) setting, you have continuity between the ECM E27 connector/pin and the Immobilizer connector pin 2 red/blue wire? This would run through the C406 connector plugged in.
I did see the very low voltage readings on the video with the test light, I saw 7 and 8 volts at some points, then 11 at some other fuses. That low voltage is going to be an issue that needs to be resolved first and will most likely take care of the starting issue. With the immobilizer flashing, the ECM is disabling the injectors from firing as a security measure. And I would get the battery charged up, testing with the key on is only going to cause it to drop lower and not help with getting accurate readings. I keep a battery maintainer on when doing diagnostics that require the key to be On for long periods such as this.
The static (at rest) battery voltage should be at least 12.6v when testing. This is because by the time the voltage gets to the ECM going through connectors it will drop lower due to voltage drop on connectors which is normal.

***But you want to see what fuses are reading that low 7 and 8 volts in that under hood fuse box to start with, write down which fuses have low voltage, so we know what circuits to focus our attention on. Once we know the fuses that are low, we can go through the power distribution wiring diagrams and see where the power for those specific fuses comes from and start to track down their trouble areas. Also make sure the battery terminals are clean and tight. You would be surprised by the amount of voltage drop that can happen from the battery post itself and the harness terminal its connected to.

Another issue here you mentioned is the cluster being on all the time, I didn't see it on in the video where you turned the key On, and then cranked it. I did see the wrench light (check engine light) come on for a few seconds there, but also the flashing Key. So has the cluster issue gone away? If it's still staying on now, that will run the battery down even faster when trying to test these fuses. I'd say that low voltage is most likely going to be the problem here, modules can't fully turn on and communicate with voltage that low.