Hey! I can symphatyze a lot with your post as I've been having the same problem.
Been wanting to post about books for a while but I was never really sure of how much I could get away with in terms of talking about the plot.

I don't know if the various publishing front-ends such as Peakd allow you to mark portions of your text as spoilers but maybe you could look into that.

In general I would say that anything that is in the first part of the book or on the cover or whatnot is fair game but if you go deeper than that it gets a bit sketchier.. but as long as you appropriately warn people beforehand there's nothing necessarily stopping you from talking about whatever you want and it's ultimately on the readers too to be careful.

I think the rule of this community is specifically to avoid spoilers but perhaps you could make a generic post about the book in here and include a link to a video of yours posted on YouTube or 3speak where you specifically talk about the plot points and details that you liked. So you would basically sepaprate the two parts, makes sense?

Also, it largely depends on the book you're blogging about.
It's more difficult to talk about a murder mystery without spoiling it because the plot will likely be its main selling point whereas it will be easier to talk in depth about some literary fiction or something more philosophical in nature.

I would try to focus on the atmosphere the book provides, the pacing, the style, the themes.. and ultimately you can make comparisons and parallels with other similar books. Talk about your experience and emotions felt while reading it. Personal thoughts that don't necessarily have to do with the book but rather with real life (ultimately, a good book should make you think about these things a bit)..

I would also just suggest you to check out other posts from this community to see how others have tackled this issue.

@papageno26/review-trifecta-my-last-three-reads

This was my first post in this community. Sadly it didn't gain too much traction but hopefully it can provide some inspiration for you.
You can post little snippets to highlight the style of the book or some specific moment that really impressed you, a theme you thought was important and so on.

You can also check out reviews such as the ones on Goodreads or video essays about books on YouTube and see what people are focusing on in their reviews without spoiling stuff and try to apply a similar method to your posts.

https://www.youtube.com/@firsttimereaders

This is a channel I discovered recently and covers single chapters and passages in detail through video essays. It focuses on Tolkien so it's quite lenghty literature to cover but perhaps a similar style of content could be adopted to cover other books as well.

Something else you could do might simply be to keep a diary of sorts with your impressions and ideas and see how they evolve throughout the read. Did you see from the start where the book was headed? Did it take you somewhere unexpected? How did you enjoy the journey?

Hopefully I've given you some ideas, although not all might be exactly applicable to hive blogging.

Anyway, I'm curious to see what you will publish in the future.