Anything that has the Uncommon or Rare tag in it's stat block, either requires a boon, or it's just not allowed in PFS play. Anything that has neither tag is considered Common. These 3 colored terms are the RARITY. This is true for ancestries, backgrounds, heritages, dedications, feats, items, etc.
So if you've found something you want, but it has the Uncommon or Rare tag, how do you discover which boon you need? That my friend, is complicated, but I will show you step-by-step how to do it here today. As an example, lets see if the Automaton ancestry is Pathfinder Society legal.
Before we get started, make sure to bookmark these 6 links. You'll need them. 👇 You can also find them on my Pathfinder Society page.
Archives of Nethys - https://2e.aonprd.com/Character Options - https://paizo.com/pathfindersociety/characteroptions
Official Pathfinder FAQ & Eratta - https://paizo.com/pathfinder/faq
Your Paizo Organized Play Account - https://paizo.com/organizedplay/myAccount
Official Pathfinder Society FAQ - https://paizo.com/pathfindersociety/faq
Step 1 - RARITY
Archives of Nethys - https://2e.aonprd.com/
Find the RARITY in the stat block. (Common, Uncommon, Rare). In this case, the Automaton is Rare. Then look for a "PFS Note" that specifies availability. In this case, there is no note. Sometimes, there will be a note that specifies who has access. So pay close attention to that in stat blocks.
Take note of which book it is found in. You need to own that book, unless it's in a Core Rulebook, the Lost Omen's: Pathfinder Society Guide, or the Lost Omen's: World Guide. If it's in one of the books I just listed, you don't need to own the book to use it.
Step 2 - AVAILABILITY
Character Options - https://paizo.com/pathfindersociety/characteroptions
Find the Availability on the Character Options page. Start by clicking on the link for the book that the ancestry is found in. In this case Guns & Gears: Remastered.
That will open the expanded Guns & Gears: Remastered section. You'll notice that it has 3 headings on this section. Standard, Limited, and Restricted.
We look for any mention of our ancestry, anywhere in this expanded view. It doesn't appear in either the Limited or Restricted section, so that makes it Standard availability. It's also not mentioned anywhere else in this section, which is good.
Now we compare our discoveries to the chart above, which is found on the Paizo Character Options page. Our ancestry is Rare, and it's availability is Standard. So we should have access and be able to find a boon for it in our Paizo Organized Play account.
Step 3 - ERATTA
Official Pathfinder FAQ & Eratta - https://paizo.com/pathfinder/faq
Now we have to see if they've nerfed our Automaton ancestry.
Please note that there is a Pathfinder FAQ & Eratta, and a Pathfinder Society FAQ, and they are 2 different websites.
On this page, look for eratta for the Guns & Gears: Remastered book. Either read it completely, or do a browser search for "Automaton". You will discover that there have been a few changes. Make note of them.
Step 4 - AcP BOONS
Your Paizo Organized Play Account - https://paizo.com/organizedplay/myAccount
Now comes the moment of truth. Log into your Paizo account and go to your Boons tab. A quick search for "Automaton" shows an Ancestry boon is available for only 80 AcP. It used to cost 160 AcP!
You'll notice there's not really a description for this boon. Ancestry boons don't have descriptions because they are so self explanatory. However, there really aren't descriptions for any boons on this list. That leads us to step 5.
Step 5 - BOON DESCRIPTIONS
I don't know why Paizo makes it so hard to find boons. Some say it's to prevent boon shopping, and murder hoboing. Well, in any case, sometimes you just need to know the boon text, because it's not listed on your Paizo account boon list. If there is a boon description, it will be listed at either of the 2 links listed below.
Official Pathfinder Society FAQ - https://paizo.com/pathfindersociety/faq
With this link, we can look up the boon text for most boons we find in our Paizo account. If you're looking for the text of a chronicle boon, you won't find it. You're not meant to find it. The only way you will see it, is to possess that chronicle sheet.
Lorespire Achievement Point Boon List - https://lorespire.paizo.com/tiki-index.php?page=pfs2guide._.Achievement-Points-Boon-List
Lorespire is the home of all Pathfinder Society specific rules, which means it's where to find boon descriptions for Pathfinder Society specific boons. Things like "Second Chance", "World Traveler", or "Radiant Wayfinder".