GrapheneOS has support for all non-end-of-life Pixels including the budget 'a' series which are available at low prices for new devices. We don't continue indefinitely supporting devices lacking updates to firmware, drivers, HALs and in practice also upstream kernel updates once those become unreasonably insecure. We do provide extended support past end-of-life but we stop once we believe it's doing more harm than good by encouraging people to use insecure devices and especially to buy those to use it against our advice. It's a privacy and security project so we can't reasonably have official support for devices where it's highly insecure.