what are the tools you used (if any)?

It is just a bunch of ideas on how to make things intuitive and a bunch of hand holding Claude Code to get exactly what I want. Underlying is plain HTML CSS and JS.

Several vendors are proposing alternative, with local Python execution with sandboxing and without local deployment of Python, leveraging WASM with Pyodide (which now supports Pandas, Duckdb, ...).

it is the case of XLWings lite https://lite.xlwings.org) and even Anaconda who partners with Microsoft for the distribution running in Azure, has developed such flavor (Anaconda Code https://www.anaconda.com/docs/tools/excel/code).

so to run native Python you end up depending on Azure. and to run Python locally you depdend on initially Web centric technologies in this case Typescript, Wasm, WebWorker...

Indeed, personally I just purchased the Onyx Boox Max 2, a 13 inches e-ink tablet running Android (6.0). quite expensive (some will say far too expensive if compared to iPad pro, but keep in mind its niche market, small company, R&D). PDF is quite well support, and now we start seeing Android apps with special mode for e-ink (Librera).