I've been using the free, open-source React Admin https://marmelab.com/react-admin/ framework for this use case, and I really like how it works and how little code I need to write. I used it to quickly build an internal CMS, and it handles relational stuff well. For instance, if I have pieces of content, each of which can have multiple tags, it handles all the tag lookups using typical REST API calls. Also integrates well with our existing auth system (AWS Cognito).
There are some other low-code tools that have similar premises and offer things like ETL tools. We evaluated one called Retool https://retool.com and it seemed pretty cool, but because it's a per-user pricing model, the costs can be pretty substantial when you have a lot of people using the tool.
Since you mentioned Retool and react admin, take a look at Appsmith. It's an open source low code tool similar to Retool.
https://github.com/appsmithorg/appsmith
I'm a co-founder of the project and we started this because there was no open source project that made it easy to build highly custom admin panels and internal tools.
We created Lowdefy (co-founder here) to built web apps fast and it is really working well for us and our customers. We’ve already rolled out a few enterprise level apps in record time and the platform really scales well as apps evolve and get really complicated. Even developing apps as a team is a breeze since you are working with yaml / json which is easy to code review, copy, paste, find and replace.
I used a cookie cutter project with react-admin and fastapi but I was kind of bummed with how much packages were pulled in and how slow builds were. I figure I need to go in there and figure out all the stuff I don’t need, but after that I realized it would be hard to get buy-in with the others on my team.
Still, I believe something like this is a good future for internal apps.
I've done three production apps with React Admin and its predecessor ng-admin. They do what they say on the tin. Integrating custom components with React Admin works well and is a tremendous affordance.
There are some other low-code tools that have similar premises and offer things like ETL tools. We evaluated one called Retool https://retool.com and it seemed pretty cool, but because it's a per-user pricing model, the costs can be pretty substantial when you have a lot of people using the tool.