looks like a decent configuration to me. two disk groups.If you have 8 hosts you could consider going RAID-5 with vSAN Advanced, that would provide some significant capacity returns (much lower overhead). Of course without understanding the workload it is difficult to say how it will behave. But if it is hybrid now then this looks like a good step up!
seems that somehow I missed you feedback. In the meantime our scope changed a little bit. We'll still start 2 DG's, each with 1 x 1,6TB NVMe (HPE can not deliver 800GB or they are more expensive for us), and 3 x 3,84 TB RI SSD. The server will be DL380Gen10 with 3 disk cages, so that we can use max. 6 NVMe's and 18 SFF SSD's if needed. HPE uses one P408i-a controller + SAS Riser for this setup. I had some doubts regarding this controller - even if the controller is only used on pass-through - but HPE confirmed that this controller is sufficient, even with 3 DG's with 3 NVME's and 18 SSDs. HPE vSAN ready nodes I found also use only one controller. Can you confirm this?