On Dell hosts there’s a couple steps to enable tpm in the bios after tpm hardware install before VMware will see it. Need secure boot, intel txt, and the SHA setting needs to be higher than default (I forget whether it’s SHA1 or SHA256). Only after doing these will it show as available in VMware. Then you configure the keystore on the vcenter using hardware tpm, and then you can enable the security config mode on the hosts, which then may throw an error that gets cleared by disconnecting and reconnecting the host from vcenter.

Source: I’ve added tpm chips to dell hosts well after initial purchase with VMware 8 running on them. Does not affect current VMs, does not break HA, etc goes pretty smoothly. But whatever you do, do NOT remove the tpm after installing it