Steps to Self-Publish - Am I Missing Anything?

I’m a traditionally published author, but am helping a friend dying of cancer to self-publish his historical fiction novel. He spent 4.5 years writing a stellar manuscript, which has already been professionally edited (both developmental and line). I’d love for him to hold his book before he passes away. Toward that end, as we work quickly to see it published, I’d appreciate any feedback on whether or not I’m thinking through all of the necessary steps:

(1) Finalize manuscript (primarily a proofread edit remaining)
(2) Use Vellum or Atticus to format interior design
(3) Purchase ISBN(s) — Do I need separate ISBNs for eBook, paperback, and hard cover?
(4) Create a design brief for book cover designer
(5) Hire cover designer. Provide him/her with the design brief, page count / trim size info from Vellum / Atticus, and ISBN numbers.
(6) Upload to KDP and global distributor (not sure yet which we’ll use IngramSpark, D4D, etc.).

I know there are additional decisions to be made and secondary tasks to complete (create author website, form launch team, settle on price, etc.), but do I have the basic gist down? Thanks!