SSD Booting : low power issue

[HeviiSailor]

I am using this one, its adjustable:  https://amzn.to/3rvaHif...

I am also working on an engine sensing project like Boatingbaileys...

Wow. The diagram is a tremendous asset, Jason. Thank-you very much!

With regards to your initial concern about connecting power directly to the RPi's GPIO pins, I had/have the same concern. Since, apparently, some protection is afforded by powering via the USB C port, this is my preferred route. After having had looked at a couple of Bailey's videos again, I realised that I can use a breakout board for this purpose. Even if connecting via the USB port isn't really necessary, it still provides an ability to quickly swap-out a Pi rather than having to open things up!

Here's a shot of typical board which I plan to use with my variable power supply: 

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my schematic is attached ...

Once again, thanks for posting the schematic, Jason. 

Now that I've had a chance to go through it in detail, I have lots of questions!  Have you (or do you plan to) described/describe the ciruit and its rationale somewhere?