I want to start off by saying I am just a community member so my comments are not directly indicative of the core teams. I will try to answer your questions how I understand them.
pNodes were created as a means to allow anyone to be a part of Incognito regardless of technical ability/understanding. They have made a truly plug-n-play hardware available to the masses allowing even grandparents and children to join in.
Incognito also allows users (with more technical skills) to set up their own vNodes (with code provided on GitHub) on their own hardware.
Incognito, to my knowledge, is the only project to think long term on how to include everyone regardless of price increases in crypto.
You can choose to fully stake a vNode or pNode with the cost currently being ~5,000usd at today’s prices. If someone can not afford this they can choose to purchase a pNode and stake with community-funded stake making some 35% of the payouts with no upfront cost to them (besides the cost of the pNode). Over time, after they have enough to fully stake their pNode they can switch 100% self staked and receive all the rewards.
Incognito goes one step more and allows staking of PRV without ownership of any node generating users with as little as 1 PRV, 21% apy (current rate; subject to change).
So as you can see Incognito is accessible to anyone no matter current PRV holdings. Most other cryptocurrencies that I am familiar with require you to have a full stake in order to participate.