I love to read and constantly struggle with finding good book reccomendations. I've considered building a book reccoemdation platform around this problem.
I too have found good reads and Amazon to be near useless for discovery. Some of the tricks I use are as follows.
Podcasts: any time I'm listening to someone interesting on a podcast and they mention a book I write it down. Bonus points if the podcast host frequently asks guests for book reccomendations (good podcasts for this strategy include Tim Ferris, Tyler Cowen, and Lex Friedman)
Personal reccomendations: I ask everyone I know who reads if they've read any good books lately. That tends to be a good way to get out of my bubble too.
Google + reddit: searching for threads on reddit about good books. The /r/books subreddit tends to focus on bizare minuta about reading rather than book recommendations, you're looking for threads on subreddits like /r/AskReddit. Good queries include "best book you've ever read Reddit", "favorite book of all time Reddit", "book that changed your life Reddit". You can also narrow it to the genre you're looking for "favorite sci-fi book of all time Reddit"
Google + hacker news: exact same strategy as above but with hacker news instead of Reddit. There are also several book aggregators that scrape hacker news. I prefer the search method but of those sites this one is my favorite: https://hackernewsbooks.com/
References from other books: If I'm reading a book I like and another book is referenced I'll write it down as a potential next book. If there is a concept I'm unfamiliar with but sounds interesting I'll use the Reddit or hacker news method to try to find good books about that topic. If there is an author I like I'll also try to read all their books.
TikTok: I've found TikTok to be the best social network for reccomendations generally, that also applies to books. Lots of channels dedicated to book reccomendations usually by genre.
You mentioned non-fiction specifically. Something I've become a big fan of recently is textbooks where possible. Usually it's much more detailed and complete than say a pop science book. Most textbooks are terrible so make sure you use the Reddit or hacker news method to find the best textbook(s) for the relevant subject.
Happy reading!