Your best bet is using a camera app like Obscura or Halide instead of the built-in Camera app. They let you manually adjust focus and exposure and such, and actually save the picture you take (with optional AI touchups). Source: almost 2 years ago

You can see more here: https://obscura.camera/. Source: almost 2 years ago

I haven't used either of these personally but darktable and Raw Therapee are two open-source options that seem to get recommended a lot. Source: 11 months ago

Some closing links to edit images, just because I dislike Adobe as a company :P. Https://krita.org/en/ - a great and free image editing tool, focused on painting but very much funtional in many ways you would also find in Photoshop. Https://www.photopea.com/ - an online alternative of Photoshop. Https://www.darktable.org/ - A free lightroom alternative to edit raw photos with. Http://rawtherapee.com/ - Dito for... Source: 12 months ago

Is GIMP not an option? Raw Therapee? Darktable? Source: about 1 year ago

Darktable and RawTherapee for editing raw photos. Source: about 1 year ago

I use digikam to organise my photos and rawtherapee to edit. Both free and open source, more than enough capability for non-pro use. Source: over 1 year ago