what you describe would be an ardous journey… if the mentioned macbooks cost like $500. or $1000. truly, that sorta thing is nothing short of masochistic and no sane person should bother with that.
you’re making broad statements based on very shitty hardware - 4 gig dual-core laptop isn’t a very representative experience when you can get solid workstations for pocket change.
the macbooks I get are in the $20 region and for that kinda “money” I get absolute top-notch quality hardware, that, although dated, is more than adequate for the vast majority of uses. spending a coupla minutes to tweak it post-install isn’t a huge price to pay.
here’s my headless 2014 MBP (i7-4770HQ with 16 GB, Intel Iris) doing its thing. was sold “for parts” due to busted screen for $25 ($40 asking).

so, yeah, dicking around with broadcom’s stack is a thing, but it’s a thing that you do once and then it just works. I’m as bleeding edge as reasonably possible (F43) on all models I run and I haven’t got any issues, akmod builds the driver on every kernel install, which if you’re doing actual work on the thing isn’t something you’re doing often.
as to how to install without LAN, you use your Android phone and tether its Wifi via USB. after five minutes (full system upgrade, install broadcom-wl via rpmfusion for e.g. Fedora) you’re done. or, use the netinstall thing the same way. there’s also a buncha stuff needed to make the experience better (undervolt, LID0 wake events, etc)
not sure about Airs but MBP 2015 models (possibly 2013/14 as well) can be retrofitted with a $5 adapter board that lets you fit a regular Intel M.2 NGFF in there, eliminating the tainted kernel issue.




take a look at macast, you can send it videos from e.g. your phone (youtube, jellyfin, .mp4/mkv, etc) and it uses mpv under the hood and plays it full screen. I imagine that’s what chromecast does (?) but have no experience with it as I wouldn’t let the stinky fucker on my LAN.