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InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
If you feel the limit of the lack of integration in Emacs than Ledger (or the new and super-simple https://github.com/md-arif-shaikh/expenses if you want basic stuff) is probably the most mature and well known option. If not and HB is enough for you you still have your data and in the end HB is just a GUI around a custom XML storage, so if really needed in a not so near future you can import out of HB in other software. No cloud/third party services involved.
If you are willing to write personal tools, the very first IME will be a way to import transactions from your bank(s) out of the formats they offer, avoid duplication, handling "history changes" (for instance debit cards in most (all?) countries appear immediately then change when the payment processors gives details to the bank) etc. That can be a nice intro/base https://github.com/egh/ledger-autosync but for stocks is more complicated: much depend of your trading choices: if you do rare put/call bank export + "live" quote from Yahoo Finance might be ok, if you do day trading or scalping you need a more "near-real time" source of data, and that's are not free at least in EU (France/Italy/Sweden AFAIK), there are some SIM that offer rest APIs with various price policies...