How to clean install of MacOS on 2018 MBP I have a 13" 2018 MacBook Pro. My System Integrity Protection is off, and T2 security is set to None. After an update to MacOS Catalina 10.15.3, my mac would stay at the bootup screen with an apple logo. I salvaged all my data in recovery mode and tried to reinstall MacOS from there. I ended up getting A software update is required to use this startup disk error in recovery. I then completely wiped the internal SSD, and using another mac and disk drill made a bootable USB with MacOS 10.15.3. I booted that and got the same A software update is required to use this startup disk error in recovery. I tried to reset the mac to its original OS after that with Shift+Option+Command+R, but after loading with a rotating earth for a few minutes I get an exclamation mark sign over that earth with the following below it:  

apple.com/support  
-1008F


Regarding the inability to boot the MacOS USB stick, I've read that the newer macs can only boot from APFS drives. However, I do not know how to do that. After using disk drill to flash MacOS to a USB, I tried using a  disk utility option Convert to APFS..., but that threw an error.

I have no idea what to do anymore, and would rather not go to an apple store to fix this. Is it even possible for a genius bar person to fix the software? How could I fix this myself? 
I do have access to a few decently sized USB drives and a tri boot Windows/Linux/MacOS computer, but no professional tools.

I would like to add I have not been able to install linux either onto my Mac, and not even rEFInd.
According to everymac.com, your 2018 Mac should be able to run macOS 10.13.6. You could try using the 2014 Mac to download High Sierra from this website.  This download should be the latest High Sierra macOS 10.13.6. You can the use the instructions from this website to transfer High Sierra to a flash drive. After booting from the flash drive, use the Disk Utility to erase and APFS format the internal drive. Finally, try installing High Sierra. If successful, then you can try upgrading to Catalina.