how to make a engineering drawing inspection ballooning application?

hi everyone👋 !

I'm exploring an opportunity to make a SaaS for engineering job shops. Could you please suggest what tech stacks I should explore?

What does the app do?

1. ✏️ Eliminates manual data entry and paperwork
2. 📊 Provides insights on the manufacturing processes
3. 📄 Generates reports easily

The MVP needs to do this:

1. users can upload and display pdf engineering drawings
2. users can draw a selection box over a dimension
3. app needs to optically recognize the selection box and output a dimension
4. output dimensions can then be used for report generation and insights discovery

An example of an engineering software that illustrates the points above:
https://youtu.be/Nt-8T0zyrvw?t=93

Why make a SaaS if there are such software out there?
Such software usually:

1. cost quite a bit
2. require installation and maintenance
3. run offline and data can't be shared easily

I've intermediate experience in building CRUD apps using Rails & Django. Not much experience in building highly interactive apps. Appreciate your help in providing suggestions, thanks!