I think the main point here is that the OP won't have the automatic right to work in Spain after the end of transition. Same as a Brit can't up and go to the US or Australia and start applying for jobs. It's not just a case of being the last to be given a job, a Spanish employer cannot legally employ him if he doesn't have a work permit.
He would need a visa in order move to Spain, and he won't get a visa that allows him to go there and look for work. Either he needs a job lined up in advance with an employer who has agreed to "sponsor" him for a work permit and visa for him, or he needs a private income or enough savings to live off for the duration of the visa and he won't be allowed to work.
The end of freedom of movement means what it says.

I think ..... The turkeys did not understand what they were voting for.