If you have a small PBN and diversify your project's backlink profile with other types of links, then most of the times you don't need to worry too much about footprints. Avoiding PBN footprints is a must, but remember - the more effort you put into it, the more expensive it will be for you (time is worth too!). There is this thing called budget, that is also important in SEO. It's a numbers game, you need some amount of good PBN links that work, are indexed and don't leave footprints for G. In general, as long as PBN sites stay indexed, you're good. So why would you want to put more money and time into it than necessary?
To sum up the long list, IMO most people who own a small PBN, should just make sure to do the following:
- different hosting, IP, nameservers
- different registrar, whois information (privacy)
- different CMS (wp, html etc.) and theme / design / code
- niche relevant unique and readable content
- natural looking site with images / videos, subpages (contact)
- different anchors pointing to MS together with few different authority links
Long to-do lists can have correct information, but may often show the task to be more complicated than it actually is.
Don't think I do my PBNs carelessly, it's the opposite - I often feel I put too much love into it. And they work great!