I have an N900 as my daily driver. It has SMS and MMS history from quite a long period. I can export the SMSes in CSV format easily (it's just an sqlite database).
What's the best method to transfer these to Android (preferably without some paid app).
I found this https://github.com/teleshoes/Android-SMS-DB-importer but not much else.
Same applies for contacts. I can always export them to the SIM card of course and import back in, but SIM card only allows you to have one phone number per contact and not ancillary info (company, etc). I can export them as VCFs from the N900.
I'd prefer to avoid syncing them via a Google account. In fact, I hope to run my Android with minimal interactions with google, except for Play store.
1) I went from sailfish to android, and just used scp (termux) to copy the file. Your N900 probably has an ssh server, so this should work fine. Make sure both devices are connected to the same WiFi AP.
2) Alternatively, on the N900 (I am assuming you have standard shell access). (install python and) Run the built in python web server with:
python -m http.server
or the correct library for your python version. This creates a web server at port 8000. Simply navigate to that page on the android and download the file.
3) bluetooth transfer
4) insert a USB stick in the OTG port of the n900, copy the file to the USB, then transfer to the android (I'm just trying to remember if the n900 had OTG.....)
5) (for proper pencil heads only) You can use USB networking, but that really is no different to using wifi, just faster. For a small file like the VCF, it won't make a difference.
I used method 1