Yeah this is a tough one. The whole think positive thing generally comes from two places - firstly people genuinely trying to help, who know that finding positive and good stuff in the midst of this tough moment is important to help you get through. The second is a human instinct in crisis to suppress negative emotions and 'get on with it' - and focusing on good things, refusing to admit the challenges - that whole 'head down let's do this' attitude is all part of doing that.
The thing is, this isn't a short term crisis, is it? It's been nearly a year! So what you are feeling - that sense of limbo and frustration and just being a bit over 'thinking positive' - is all a healthy response to where you are at - especially at your age and life stage when you want to be able to plan for your next season after school or college - but can't right now because you don't know where the world will be even in the next month never mind the next year. It is incredibly frustrating!!
In a longer season of challenge like this it is really normal for your mind to actually start to want to process some of the more difficult stuff - and to do that it brings it to the surface more - so you might feel like some of this less positive stuff is very 'present' in your thoughts right now - annoying if you are trying not to think about it. And also your mind triggers emotions to grab your attention - so you might be feeling more frustration, anxiety, sadness etc at the moment too.
Actually the best approach in this moment is a good balance - recognising the negative and trying to find some spaces to chat about that stuff through and help your brain process it (this helps get it out of your mind in the long run as your brain can let go of it a bit) but also yes - hunting down positive and good stuff even in the midst of so much that is a pain in the neck. Becuase even in life's toughest times good things do still exist - they may be small, or not the things we wish we could do but they are out there - laughs with mates on a zoom call or a funny text, or going for a run with someone, or a really great movie or joining an online escape room ...
Becuase like you say - although this won't last forever, it is hard to see the end in sight JUST yet - hopefully it isn't too far away. So perhaps you'd find it easier to think about these skills of persuing positive stuff as a bit more like treading water whilst you wait for the tide to turn. Its all about finding ways to keep ourselves going through this long winter ...