HELP!!!!!!!!

I'm entering the world of digital photography for the first time and am after a mirrorless camera to use with my vintage M42 lenses (with an adapter), mainly my MC Rokkor-pf 50mm f1.7 lens. I eventually plan to buy some modern lenses but for now am just looking for a good camera body and an adapter. I don't have a huge budget so will be buying second hand an looking to spend ~$800.

I essentially have three things I'm after:

1. full frame so no crop factor with my old lenses,
2. the tangible, button-per-function retro SLR style of body e.g. fujifilm x series and the nikon zf,
3. if possible, some sort of assistance with the manual focus on the lens ie focus peaking, magnification etc

The only camera I've found so far that checks all the boxes is the nikon zf, but it's out of my budget. Can anyone point me to some alternative models within budget-ish? Or should I abandon my pursuit of the retro body style and get a sony etc. OR should I just get an APS-C sensor, fujifilm xt3 type of thing and accept 1.5x crop factor.

I'm not entirely opposed to DSLRs but love the compactness of the mirrorless, and haven't come across any DSLRs that have the retro body look.

Also FYI I'm just after a camera for photography, not for video.

Any help appreciated, thanks