Should I know openings?

No.

Just kidding.

Well.....

Know the principles. Play one opening all the time as white and play solidly as black. 

For example, I play QGD which is practically a system whereby I answer 1. ...d5 with c4 and Nc3 then from there it's a combination of either bringing my dark-squared bishop out first or just playing e3 and Nf3. I keep it easy. Of course, always react to what your opponent might be doing in case they play sub-optimally. Get yourself a small "system" like this where you know the first few moves you like to play as white and how opponents typically respond.

As black I just play solidly. I get a pawn or two fighting in the center, get at least three minors out and castle. That's it! I'm sure that's good enough for me to get to 90% classical lichess.

That's the quickest way to get a solid game started. Of course you'll want to start branching out with white at some point, otherwise you'll miss a lot. For example, I don't play 1. e4 so I never face the sicilian. That's something I'll want to start doing, perhaps after I reach my classical goal. It'll be interesting to track my progress with the change to 1. e4.

I think the goal for advanced beginners in the opening is to safely accomplish the opening principles without dropping material or having more than a +/- 1.0 engine evaluation. If you can do that in nine games out of ten you're doing well.

Familiarity with the opening names
I wouldn't concern myself with memorizing ten different openings twenty lines deep, but I do want to start familiarizing myself with names of the common openings.

When I watch a streamer, they might say, "We're going into the dutch here" or, "This is the scotch game." I have some ideas on a distinguishing move in openings they might play (for example, I know Dutch means an early f5 from black but that's pretty much it!) but I always thought it'd be nice to identify them more confidently. This reddit post provided a pretty good way to study the openings on a surface level:

https://www.reddit.com/r/chess/comments/aw7jcw/chess_openings_updated/

Almost like a "name that tune" game, I'd like to be able to see the first four or fives moves from anything in this table and be able to identify the name of the opening. I'm not going to study all of them, but I think some brief familiarity can go a long way with them.

Here's the .jpg of the chart.

You could do this any number of ways. Maybe you break it up with the 1. e4 e5 lines and memorize them. Cover up the common name of the opening as you go down the line guessing the names. Reminds me of memorizing things 10 minutes before a college exam :/ but it's something! After this you could just look at the names of the openings from the chart, then open up the analysis board in lichess and try to play out the moves that make up that opening. The analysis board will label the opening for you so you got the moves correct!

Play Correspondence to Learn to Play Solidly
Correspondence is a great way to learn chess in general. I found a great way to check my opening ideas with it too. I usually have correspondence games ongoing on my phone and there's a simple way to check the analysis board in any given position. From that you can access an opening book that shows you the most common moves from GM games! I don't consult it right away in the opening but what I do is look at the position and come up with my candidate moves and I sometimes rank them. Then I check with the opening book to see if my move was one of the top-played moves. This can be an invaluable way to see how you're doing with opening principles, prophylaxis moves, pawn breaks et cetera without blindly memorizing lines.