Her statement in that video about politics is pretty vague. Whether or not it would be difficult for her to be neutral on political matters depends on what aspect of politics/governance she would have wanted to take on in her career and what about it interests her.
She was on a diplomatic career track before shifting into acting; in many ways the job of a royal is all about diplomacy. It should be noted that the Foreign Service Exam has a reputation for being very difficult. The written portion covers a very broad range of subjects and the interview phase involves having to troubleshoot complicated, thorny problems very quickly while a panel watches. She must have passed it, though, to have worked in the embassy in Argentina.
There are a lot of political positions within government agencies that are about championing/enacting policies related to the welfare of citizens. In monarchies, the next step after passing those policies through the government seems to be snagging some member of the royal family to highlight the new programs through patronages, attending key events, etc. So if that's what interested her, there's still very much a role to play.
But yes, if what she wanted to do was run for an elected office, play a role in campaigns or crafting laws, the royal life might be frustrating for her.
The good news for Meghan is that she seems to have already had a pretty good idea of what she wants to do with her life and what she finds fulfilling. She's experienced a dramatic change in career already, when she shifted from foreign service to acting. So that surely puts her in a good position to really think through whether her goals and aspirations line up well with the kind of life Harry has to offer. We'll just have to "stay tuned" to see what she and her prince decide on that matter.