Oh man, I totally feel your pain! When I was grinding through my thesis, I found a couple of lifesavers that are honestly amazing and wont break the bank. You should definitely check these out:

• Claude 3.5 Sonnet for super accurate summaries and reasoning.
• Microsoft Copilot Pro if you have access via your uni account. Just paste the text directly and youll be done in no time. You got this!

I feel you on the privacy stuff, seriously. If you want to keep your documents local and avoid uploading them to some random server, you really should look into GPT4All Local LLM. It lets you run models entirely on your own hardware so nothing leaves your machine, which is a huge relief for sensitive research. It works well once you get it set up and I have no complaints about the accuracy. Another solid option is using Obsidian Note-taking App, especially if you pair it with a plugin like Text Generator or Smart Connections. Since the files stay on your drive, you dont have to worry about anyone else skimming your data. It takes a little effort to configure but it is basically the safest way to handle your lit review. Just stick to a local setup and you wont have to stress about privacy.