Leading questions:
Representative vs Direct Democracy?
Unitary or Federal?
Presidential or Parliamentary?
How much separations of powers should there be? In presidential systems, such as the United States of America, there is often deadlock between the executive and legislature. In parliamentary systems, the head of government is elected by legislature, therefore, there is practically no deadlock as long as theres is majority support of the executive in the legislature (although, there can still be courts to determine constitutionality of policiss). Would you prefer more checks and balances, but can also result in more deadlock, or a government more easily able to enact policies, for better or for worse?
Electoral method? FPTP? Two-Round? Ranked-Choice/Single-Transferable Vote? What about legislature? Should there be local districts? Single or Multi member districts? Proportional-representation based on votes for a party? If so, how should the party-lists be determined?
Should anti-democratic parties be banned? Or should all parties be allowed to compete in elections, regardless of ideology? In Germany, they practice what's called "Defensive Democracy" which bans any political parties (and their successors) that are anti-democratic. Some of banned political parties include the nazi party.
How easy or difficult should the constitution br allowed to be changed? Majority support or some type of supermajority support?
Should we really elect officials, or randomly select them via sortition?
These are just some topics to think about, you don't have to answer all of them.
Edit: Clarified some things
You aren't wrong, trust is obviously very important.
What I am trying to describe is the emergence of an alternative system that people could choose to use based on its own merit, similar to how bitcoin has emerged. While many people still don't trust an idea like bitcoin, already many millions of people do trust it, and the aggregate value of all bitcoin is currently something like half a trillion USD because of this, because of the network effect, because many people do give value to it. As the years go on, as bitcoin continues to fulfill its basic promise of being trustworthy, of functioning as intended, more people will continue to trust it and use it because, while flawed, it promises a degree of inherent trust and functionality that is superior to the incumbent alternative fiat currencies that continue to lose more and more relative value every year due to irresponsibility and corruption of the central banks.
In this sense, a decentralized digital identity network would simply be a more functionally decentralized social network. The topic here is trust, and here we are in the fediverse because centralized for-profit social media companies are not preferred by people here, because of trust and other reasons. As the years go on, the experience of for-profit social media companies will have to compete with the experience of fediverse social media, and if fediverse social media is better, it will eventually emerge as a preferred viable alternative, and maybe even the predominant form of social media. People can choose to use it or not, but because of the network effect, as more people do use it, it increases its inherent value, which causes more people to trust it and use it, which continues to increase the inherent value, etc., until some thresholds are reached.
This would be true also of a hypothetical decentralized identity network. People could choose to use it or not, based on its merits. Many people would choose not to use it because they don't trust it. But, as it would continue to grow and evolve and improve, like bitcoin, or like the fediverse, a larger number of people would use it and trust it despite it being relatively niche, it would continue to demonstrate itself as a viable alternative. In such a scenario of emerging naturally by competing with the incumbent systems, it is not inconceivable that such a system could eventually surpass a threshold and become the predominant social network and identity system in the world, that also provides effective functionality of things like voting on issues.