The point of serverless for vendors is lock-in. Everything else about it is an annoyance, from their side (having to manage lifecycle, controlling load in shared engines, measuring resource usage...). But it locks people in and can be slapped with basically-arbitrary prices. The incentives to set standards are exactly zero, because once all providers support them and easy portability is achieved, it becomes a race to the bottom on price. Unless vendors can come up with some extra value-added service on top and choose to commoditize away the serverless layer, there won’t be any standard.