Haven’t read so can’t tell you but you will find info at https://leminal.space/post/11699480

Can second that email works great to send Epub, never had issues in years

I have used darktable, but doesn’t seem to fill your need as it is more a lightroom replacement than Photoshop https://www.darktable.org/

Home assistant has a voice assistant but it isn’t a voice assistant. Also, you are correct it is made to control a smart home (at the moment) that also include music threw external provider (or local files) but you can’t search the internet threw it. You can either install it locally or pay for home assistant subscription which include voice assistant threw cloud.