LineageOS runs fine without Play Services. It's actually the default mode. It just limits your app choices. My needs are simple so I don't really mind, and I appreciate the improved battery life and speed.
It turns out many apps from the Play Store don't actually have a hard dependency on Play Services. Example: Slack works, except for notifications and (IIRC) receiving calls, which is good enough if you don't need to be reachable all the time.
I run LineageOS v13 now (Galaxy Nexus), and before that Cyanogenmod back to v7 (maybe v6 not sure) and have never had Gapps installed, its been F-Droid all the way. I guess that means I can't appreciate the improved battery life or speed..
I use Yalp Store to use apps from the Play Store and even though almost all of them "require" Play Services, most work just fine and worst case scenario they have a nagging screen about requiring Play Services but work just fine.
Same with Discord. I don't get any notifications from Discord on my de-Googled LineageOS devices, but the application works just fine (although I had to silence its constant notifications about Play Services).
By default, LineageOS does NOT include google play services. And it works just fine if you don't expect to use apps which "require" google play services.
Does this still require you to essentially nerf application signing in order to spoof some google play crap? If so, that's really not a viable solution.
The newer version of signature spoofing patch (included in microG's LineageOS fork) allows you to control the spoofing and make sure that it's only used when necessary and permitted, so I'd say the answer is "no".
Interesting. I know the microG folks tried to upstream a patch to Cyanogenmod, which the devs shot down almost immediately.. So you're saying that the microG folks are now maintaining a fork of LineageOS? If it's not tracking VERY closely to upstream LineageOS, then it's probably not worth it.