Sure. There are still a lot of unknowns on what the full effects will be, but I'll explain what I know so far. The issue with a lot of the sweeping statements that Apple and Facebook make is that there is a whole lot of nuance. I imagine most people won't read much of what I write, but here goes. I run a three-person company and we make iOS and Android card games. We make money by showing ads or letting people pay to remove them (spoiler alert: nobody pays to remove them) in our apps and we get users for our games by paying for advertising to get users into our apps.
Apple's changes basically will get rid of the identifier that lets people measure how effective their ads are because they can't match up someone who installs an app with the ad that brought them to the app. This is Facebook's argument. They have some statistic about how much less effective ads will be able to targeted. There is some truth to that. I suspect our ad rates will go down and we will earn less money. We will also have a have a harder time time figuring out which ads are the most effective. If I run an ad for my app on Facebook, Apple Search, and in a bunch of other apps, I won't know which ad brought in the good users (ie ones that spend a lot of time in my app) -except Apple Search, because Apple is allowed to track still.
But WAIT - Apple announced a fix for all of these privacy issues - at WWDC they said they had a privacy friendly way that ad networks could use that would allow them to still do ad measurement (what I've been talking about above) in an anonymous way. This "privacy friendly ad network" that Apple has created is called SKAdNetwork. The problem is Apple's implementation is very buggy and has all sorts of weird limitations - like any measurement has to happen within the first 24 hours after an ad is tapped on. What you are going to see is within a few months of Apple's enforcement of Advertising Tracking Transparency - is that as apps switch over to using SKAdNetwork, which doesn't require the ATT Prompt and goes through Apple, apps will become very aggressive to try and get your to "convert" in your first 24 hours of using the app. They'll also be more aggressive about trying to collect e-mail addresses or another login so that they have another way that they can keep track of you now that they can't use the old tracking identifier.
TLDR:
How am I, a small business owner, caught in the middle (we make card game apps that are advertising dependent)?
Our revenue will likely go down and our ability to be able to acquire users will become harder to measure. We also need to switch over wait for all of our ad networks (Facebook, Google, etc.) to update their code to use Apple somewhat buggy ad tracking tool that wasn't super well thought out. Our business will survive. We've had a boost this year with people shifting their attention to using our apps during the pandemic to kill time. But when people get back to normal we could see a significant drop-off of users in addition to the issues I talked about above.