Dedicated IP
A sending IP reserved for one customer.
A dedicated IP isolates a senders reputation from the shared pool. Useful at high volume (1M+/mo) or for regulated industries that need predictable reputation. Below that volume, a dedicated IP can hurt deliverability because mailbox providers cannot build a reputation profile.
reading this as early-stage startups
At an early stage the deciding factors are what the free tier actually covers, what the first paid invoice looks like, and how much of a founding engineer's week the setup costs. Feature depth that only matters at a million sends a month is noise until it is not.
Applied to dedicated ip, that means weighing free tier, best published rate per 1,000, entry price, and developer experience ahead of the rest, against a waitlist, a launch announcement, onboarding email, and the first transactional sends.