How do you go Enterprise without ruining a self-serve app?

Our product was originally built for individual creators who loved the instant sign-up and self-serve checkout process. Lately, though, larger enterprises are reaching out asking for custom security reviews, SSO, and dedicated account management. We want to move upmarket to capture that revenue, but building out these enterprise-only gates is starting to clutter our lightweight product roadmap.
How do you pivot toward enterprise sales without neglecting the solo users who made your brand cool in the first place?