I definitely didn't mean to imply that you needed an SRE/Devops for starting off. The OP just came across as sounding like you don't need SRE/Devops in general if you use Serverless, which from my experience at multiple orgs just seems idealist.

I'd argue that the need for someone focused on SRE/Devops comes from factors that are mostly unrelated to whether or not you go serverless.