How to replace a developer as a non-technical founder?

I’m the founder (non-technical) of a MedTech B2B SaaS. We initially had a CTO but they left about 6m ago. The platform was mostly built, so we just stuck with having our full stack developer to reduce burn. Unfortunately our full stack developer is leaving too now. Would appreciate any advice on what I should look for when replacing them? Key things to ask at interview? How to manage that whole handover process. As I’m not technical I haven’t been involved in coding at any level and have a very surface level understanding. TIA