The speaker of the house in the UK has enormous discretionary power about the order of business in the house. Bercow didn’t do anything illegal, nor did he do anything that has never been done before, nor did he break any rules that were written down. He just did something that hasn’t been done in a while. Something that is fully within his authority to do. The rule that he broke is an unwritten one that says we generally don’t do things that way, not that we can’t, just that we generally don’t do it that way.
Any bank guarantees that may or may not have been done were done within the full authority of government officials. There were no changes to the law and nothing illegal was done. The Irish government can guarantee any debts of anyone individual any time it wants. It has that full authority.
No one has the authority to make insurance contracts cross countries still be valid after Brexit. More importantly, no government has the authority to compel companies to ignore the law around safety standards and all other regulations concerning import/export of goods and services.
In order for things to continue smoothly someone has to actively decide to do something illegal.