@uint8_t I used digiKam¹ for a while. It got the job done. I'm currently trying Rapid Photo Downloader² which has a nice interface but fewer features. In theory gThumb can do some of this management stuff too but I've only ever used it as a viewer.
@KnowPresent as viewer I tend to use xnview; it isn't open source but freeware, and is much faster than anything else I ever tried
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