Apologies for the delayed response. I would further explore improving the performance of Power Apps in this case.
You mentioned that you have tried Power Apps, but it was very slow when the datasets were very large. This might be due to some performance issues that can be improved by following some tips and best practices. For example, you can use the Concurrent function to load multiple datasets simultaneously, write formulas that use delegation to filter data in the cloud, cache data in collections and variables to reduce network calls, limit the size of collections to avoid memory issues8, and enable DelayOutput for text input controls to avoid unnecessary recalculations. You can find more performance optimization guidelines in the links below
https://learn.microsoft.com/en-us/power-apps/maker/canvas-apps/performance-tips
I recommend reaching out to our Power Apps experts on their dedicated forum. They will be able to assist you and provide better suggestions.
https://powerusers.microsoft.com/t5/Power-Apps-Community/ct-p/PowerApps1
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