Smooth and bright interior lightmapping is not possible, change my mind

For a house scene, is there any way to get decent looking lightmaps? I've experimented with literally every single setting and haven't found a solution yet.

Mods deleted all my screenshots because I posted in the "wrong forum". Anyone know how to get my screenshots back? They just straight up deleted it, no warning, didn't say which forum to post it in, nothing. Not sure how that's tolerable. Anyway if I could post them you would see, it's not as bad in the super bright areas, the dark areas are the worst, but it's still bad all around. There's glowing edges all over, seams on the floor, light and shadows in place where they shouldn't be, and artifacts everywhere.

I know it's not an issue with the objects' lightmap UV, I've tried setting the materials to render double sided, two-sided shadows, tried using area lights, turning off weld vertices and mesh optimization, tried literally every solution I read in the hundreds of forum pages I could find. I've made some very slight improvements but it still looks quite poor.

I don't even need perfect lighting, I'm going to use light probes for all the furniture and objects anyway, and it's supposed to be "stylized", not photorealistic. Literally just want some decent global illumination that looks smooth and bright with zero artifacts, that's all. What do I need to do here? Is baked lighting even the best solution?

(Using the Progressive GPU lightmapper on Unity 2020.2 with URP Simple Lit materials, ambient color and directional light only)

 

I personally had the same issue. I know it's not what you want to hear but I solved that issue by buying Bakery GPU lightmapper. Tons of settings, nice community on Discord and quite easy to use (but learning curve, as any asset/tool).
Only if you have an Nvidia GPU though.

 

Yeah I bought Bakery, didn't really solve my issue but it was somewhat helpful. Turns out that guaranteed artifact-free baked lighting is doesn't actually exist yet. Maybe soon!