Unless you intend to create your own CPU architecture, your own internet and your own human population, by your logic, you are always "locked in". Regarding negotiating positions, those are governed by contracts and by money, the same as with any other company.
There is no real lock-in other than the requirements of your own implementation. A lambda on AWS can just as easily be run on Kubernetes, but that means that on top of running the code that you wanted to run, you now have to run Kubernetes too. You could use a hosted Kubernetes control plane, or fully hosted setup, but according to your same logic you would now be locked in to Kubernetes.
It seems to me that you might have a very special use case, or simply not have had the scaled experience or requirements that made a lot of other vendors non-viable.
Business risk-wise, AWS is a very low risk when compared with pretty much anything else. What do you think will fail first, a custom in-house maintained setup (expensive, non-portable between companies and people) on Digital Ocean, Linode, OVH, Hetzner, etc or all AWS Availability Zones in all AWS Regions world-wide? (and we ignore the lack of IAM, lack of things like RDS, SQS, SNS etc)