You need to take note that even btw professional photo cataloging software there is 90% chance that the way the utilize whatever mix of metadata systems (there is IPTC ‘legacy’ vs ‘extended IPTC’ vs newer XML, just to start the mess) is incompatible to each other. Meaning: high chance none will read what you do in another. So DevonSphere as non-photocentric app will not be a good bet jere.
Given what you describe, I would recommend Digikam actually.
Positives:
• free
• most capable of all in terms of customizing which metadata-schemes are read and written (independent setting for both); included in this: dedicated setting to read / write Lightroom-/Adobe metadata scheme, which is a little special in some aspects as to regular IPTC
• good cataloging features, inkl hierarchical metadata, geo-data & face-recognition (onboard)
• cataloging included, w/ versatile multi-catalog system (similar to how DT handles databases)
• similar image search (very handy)
• multilingual fields (if needed)
• fast & very usable advanced search & dedicated filter system etc
Some small minuses compared to XN:
• harder to transfer/cooy metadata between images
• no custom xml field capabilities
• some special EXIF/IPTC fields are only displayed but not searchable (though negligible in 95% of cases)
Basically you could use (free) XN wherrever Digikam falls short. Though latter one covers 95% of cases and is a speedmonster
PS: a newer, commercial option specialized for finding/reading metadata from different proprietary libraries/catalogs plus all image-internal metadata is Peakto from Cyme (@ 10€/month). It throws in a verbatim AI semantic search which is a) local, b) very good. Helps for some scenarios, but needs some getting used to in terms of UI logics.