Putin is a dictator because he doesn't allow free, democratic elections. Asking for a citation that Russia is a democracy is ridiculous. You need to cite sources that it is a free democracy (if you even think that) because it's by far the more outlandish and fringy position of the two.
Fortunately the USA and Russia aren't the only two countries (or models of "democracy") out there, but in any case, the USA managed to have a change of presidency and ruling political party after a competitive election, and Trump didn't try to send Biden (or Hillary) to any gulag.
Actually if you want to get technical during the campaign trump did threaten to send Hillary to prison. Then after Trump won and probably even now democratic operatives threatened to impeach and or imprison Trump on unsubstantial grounds. So it does appear that politically motivated prosecutions exist in America too on both sides. This arguably goes back to Monica Lewinsky if not Nixon.
The media frames minor or non existent crimes to go after politicians to meet the obscure agendas of the elite that funds the media...
Even if you think that the accusations against Trump (and Hillary) are as illegitimate as the ones against Navalny, you surely have to accept there is a vast difference between impeachment (and lying about the prospects of someone being locked up) and actually sending someone to a gulag and nearly killing them?
In any case, I don't judge Putin's actions based on the standard set by Trump (which would, coincidentally, give Putin a big incentive to encourage Trump to break all the norms of good governance). Other democracies manage to have more than 2 parties, and have none of their parties campaigning on a platform of "lock [the opposition] up".
Focusing on the worst examples of America specifically to try to excuse Russia's crimes is textbook whataboutism, as I'm sure you're aware.
