When is HPE keen on us using second-hand kit?
"You can't even download BIOS and firmware (ILO, etc) for their last gen servers without a service agreement."
Wrong!
While you needed a live warranty or support contract to download BIOS updates, firmware for iLO and controllers has always been free.
And starting with Gen10 servers I believe even BIOS downloads no longer require a live warranty/support contract, just a free HPE account.