Would have switched years ago if it wasn't for Adobe. Open source equivalents to Photoshop and Lightroom are NOT viable alternatives
Not really equivalent to Lightroom, and not remotely a replacement, but there's Corel AfterShot Pro [1] (source: about 15 years ago, I was one of the (1?) proud Linux users of Bibble 5, its predecessor)
For casual use I use lightroom web and it's good enough for me, if you haven't tried it, I highly recommend.
I'm sure for some workflows it isn't sufficient but for basic edits and raw development it works quite well.