To a substantial degree these hearings are political theater in the style of the hearings on drugs in baseball a number of years past. That isn't to say they are entirely pointless, but only that there probably are other things on which the legislators might spend their time.
Most of the angst seems to be about the possibility that US voter might be misled by the fake news we used to call, variously, propaganda or campaign advocacy. The fact it appears the sources for some of it are Russian, Iranian, or possibly other is being used to whip up a panic and divert attention from the underlying facts that it does not differ materially from home grown BS and comprises a tiny part of it.
Under the first amendment, the government is severely limited in its authority to regulate communication. In particular, it generally cannot regulate content, truth, or presentation, and it cannot, within very broad limits, regulate advocacy of public policy or candidates for public office. Private sector actors like Facebook, Twitter, Google, and others including news media, can apply whatever editorial polices they wish, however restrictive they may be, or how distasteful they may be to some.
The cure for these excesses in the private sector is to not use or ignore them. If Google collects too much information, eliminate your Google accounts and use another search engine; if Facebook seems too intrusive, cancel or ignore it, along with Twitter, in which I can discern no socially redeeming value at all.
And finally, recognize that if the foreign propaganda and misinformation from Russia, Iran, or elsewhere truly is a threat to democratic governance, it is doomed anyway, because the voters are too uninformed and unintelligent in some combination to withstand the barrage of homegrown propaganda and misinformation that is a couple of orders of magnitude larger.