Its the services that lock people in
Things the hyperscalers do well is behind the scenes SDN, service connections, security and logging, bolt-on services. The lock-in comes from forcing proprietary API code as service glue. You can overcome some of this using Terraform, Ansible, Puppet, Chef etc but scripting also relies on translation into the vendor's own command line interface. Ionos will need to radically increase the number of open source services on offer, which will mean a large investment. I fear they got left behind 15 years ago due to concentrating on SMB workloads and will not be able to catch up to compete against the huge money available to the big 3.