This is more of a dAPIs team question but we’re in agreement anyway so I’ll answer
(1) All byog Beacons will be added to API3 Market just in case, without requiring a user to request them. This requires some changes to the Market design, which is what Phase 1 in [Secondary Proposal #45] dAPI Team Proposal #1 refers to. Not all of these Beacons will necessarily support aggregation upgrades (Phase 2) or coverage upgrades (Phase 4) on the Market because byog doesn’t consider if API3 will be able to find adequate number of alternative sources or would be willing to cover a kind of dAPI before deciding to set up the respective Beacon. (So for example, byog will set up a Beacon for a pair with low liquidity and that will be served as a 1 Beacon dAPI with no coverage, that appearing on the Market doesn’t mean you can buy coverage for it, which also makes aggregation obsolete. The main risk factor with such data feeds is that the underlying market is easily manipulable, and aggregation doesn’t solve that.)
(2) All dAPIs will start off as 1 byog Beacon dAPIs, and users will be able to pay to upgrade a dAPI to use as many sources as they want. There are two practical reasons for starting off with byog: (A) It allows us to maintain dAPIs with no users so that onboarding to a data feed that was never used before takes a matter of minutes (funding the respective sponsor wallet). This requires the API provider to be fine with running thousands of Beacons with no users without any compensation, and for that the incentives need to be perfectly aligned. (B) Single Beacon dAPIs are more difficult to pull off successfully compared to aggregated ones because they’re not as fault tolerant. This means we have very specific requirements from the API provider that will power them, which has proven to be a difficulty. byog’s API is built specifically to power these Beacons, and according to our monitoring it is more reliable than the previous methods of operating single-Beacon dAPIs that we have tried.