I could imagine true WYSIWYG politics, but it would need a very different temporal organizational structure than current politics.
Currwntly, politicians each have a series of meetings over time with different parties (constituents, lobbyists, domain experts, coalition members) and then at some point one of them drafts and tables a law (that's probably already been informally planned for ages among those in the know) and others vote for it (where many of those votes have probably also been informally pre-arranged for ages.)
To get WYSIWYG, every bit of all of those meetings would need to occur in the open. And likely the only way to practically accomplish that, in a “nothing up my sleeve” manner (i.e. to guarantee that there were no meetings outside of the official ones), would be to have all those meetings occur contiguously as part of one long recorded session in one place, with everyone who wants “a seat at the table” needing to operate on that session’s schedule; and where the politicians involved (i.e. those everyone else is there to influence) have a political career that starts and ends with that single session.
In other words, basically do the papal-election thing, or the sequestered-jury-trial thing: lock all the concerned parties (politicians + PAC leaders + lobbyists + etc) in a building together, and don’t let them out until they make a year’s worth of law. (But unlike either of those—record everything! Don’t allow any two people to be in the same room together without a camera.)
Only one of the things that makes what you're describing unworkable is that "concerned parties" include arbitrary members of the public. Anyone who can't afford to spend a year sequestered in a room can't so much as write a letter to their representative?
Another is that they would just agree on what to do before the official start of the process. Or learn to speak in code. Or pass notes to each other off camera etc.
The closest approximation that might actually do something would be to require the final version of any piece of legislation to be published a year before the final vote. Then the product of a backroom deal can't be enacted before anyone else has a chance to mount an opposition.
Another would be to make it easier to repeal things than to pass them. A lot of current corruption relies on the misfeature that we apply the same purposely-arduous process intended to inhibit bad things from passing as the requirement to un-pass existing bad things, so then if they can corrupt the entire process once they only have to maintain control of a single branch to prevent it from being rolled back.