Your series certainly doesn't have to build up to a big epic climax or feature dramatic story arcs imo. But it would be difficult to find people who'd want to read about completely new and unfamiliar characters just hanging out and doing nothing in particular. People who read 'pure fluff' are often into it because they already know the characters/vloggers etc and want that feeling of 'hanging out' with them because they're already attached to them.
That's not to say you can't pull off a slice-of-life featuring all original characters. People think 'slice-of-life is when no plot, and the less plot the more slice-of-life it is', but that's not entirely true. I like how this video explains it, but in general, slice-of-life only means no overarching plot.
Your individual scenes, your moments of everyday burdens and stresses with love and happiness mixed in, still have to be meaningful in some way. They need some sort of direction, or message, or punchline.
For instance, consider this scene:
- A is stressed about her job, so B gives her a hug and shows her some funny videos which makes her feel better
This is kind of boring; A and B could be anyone and the scene is only cute if you already have memories associated with A and B that makes you want to see them happy etc. The scene doesn't really say anything except I guess 'work is stressful' and 'spending time with loved ones is good for stress relief' which ... well, duh.
If I tried to improve that idea, I might come up with something like this:
- A is stressed out because her boss keeps guilt-tripping her into coming into work on her off days because 'your poor coworkers can barely keep up ever since C quit out of the blue'. So B gives her a hug and they watch a wholesome comedy about schoolkids. One of the characters in the show, X, gets a phone call from his mom telling him to come home to watch the dog because she's going out, and one of his friends is like 'screw her, if she wanted you to watch the dog she should've told you in advance'. Afterwards, A feels better.
This is ... better, at least imo. There's an overarching theme here, and it's not only enjoyable if you already know A and B, but also if you're frustrated with a manipulative authority figure in your own life; you can feel the catharsis with A when you experience the show-within-a-show through her eyes. This scene also has a(n arguably) less obvious/uncontroversial message: 'you have no obligation to take responsibility for an authority figure's failure to plan ahead' :]
So basically, if your scenes have a point, your readers can come away satisfied instead of just feeling 'damn, I could've actually done something with the last 10 minutes of my life'