Experience migrating from ESRI services to open source solutions

Hello fellow geospatial enthusiasts! My team is looking to make changes to how we deliver geospatial data and I am curious other folks have done this.

My team currently supports an ecosystem of APIs and clients with data this is statistical and geospatial nature. Historically, we have relied on publishing services using ArcGIS map, image, and feature services for our web mapping applications. However, we are reaching a quantity of data (TB), an internal hosting option that experiences frequent downtime, and a zeal for open source that has us looking into a large lift and shift.

We have already moved a lot of tabular and vector data over to Postgres/PostGIS for API endpoints and some simple geospatial functionality. For front-end web mapping applications and vector data, Martin vector tile server seems like a natural fit with PostGIS. For raster data, we are contemplating putting cloud optimized geotiffs (COGs) in object storage (something like AWS S3) and using something like TiTiler to work as a raster tile server.

How have you all handled this situation? Did you stick with or return to ESRI? What challenges popped up that you didn't expect? I want to hear the good, the bad, and any other thoughts you might have. Thanks in advance!