Can I run custom code on Adobe Commerce Cloud?

Yes, fully — ACC is just Magento 2 on AWS with managed orchestration. You ship custom modules via composer + git just like self-hosted. The constraints: (a) no kernel-level access (can’t install OS packages), (b) PHP extensions are restricted to Adobe’s supported list, (c) cron jobs run on Adobe’s schedule infrastructure. For 95% of stores, none of this matters. The remaining 5% are typically B2B with custom payment processors or ERP middleware — those need careful pre-project audit to confirm fit.