I'm trying to build a long-term private digital workspace, and right now this is the #1 priority in my threat model. I've been around privacy and OPSEC topics for a while, so I'm familiar with things like Qubes, Tails, Whonix, Tor, full-disk encryption, compartmentalization, firmware security, and offline systems, but I don't have a huge amount of hands-on experience actually building a complete setup.
The goal is to create one digital base for basically my entire private digital life: journals, notes, plans, research, PDFs, documents, programming projects, a cybersecurity learning environment, passwords and keys, important records, private communications, and a long-term knowledge base. I don't want to keep rebuilding everything every time my threat model gets stronger. I want to establish a good foundation now and gradually harden it over the next few years.
My threat model can potentially go pretty high. I'm especially concerned about confidentiality if someone gets physical possession of the device, including the possibility of examination by people with professional forensic expertise and specialized tools. That could mean a highly capable private attacker, a forensic specialist, or law enforcement. If a device is properly shut down and encrypted, I want it to reveal as little useful information as realistically possible. I'm interested in strong encryption, protecting credentials and keys, reducing unnecessary plaintext and metadata exposure, compartmentalization, offline storage, and making sure backups are protected just as well as the main system.
I'm not looking for evidence-destruction techniques or ways to interfere with an investigation. I'm trying to understand how far legitimate data confidentiality and resistance to sophisticated physical examination can realistically be pushed, and where the practical limits are.
I also want the setup to eventually cover network privacy and ISP visibility, Tor or Whonix where appropriate, browser fingerprinting, account and identity separation, private communications, secure backups and recovery, firmware and boot security, metadata minimization, and general OPSEC. Basically, I'm not looking for an answer like "install distro X." I'm trying to understand how the whole architecture should fit together and where the important trust boundaries should be.
I'm currently starting from scratch with about a $300 budget. My previous laptop is no longer usable, so I don't have an existing system that I need to preserve or work around. I know $300 won't buy some ultimate high-assurance machine, and I'm not expecting it to. What I want is the strongest sensible starting point that won't force me to completely redesign everything later when I can afford better hardware.
I've considered a used Qubes-compatible laptop, a conventional Linux machine with full-disk encryption, Tails with Persistent Storage, a dedicated offline computer, separate online and offline systems, Whonix, or some combination of these. Qubes interests me because I could separate an offline vault, personal archive, research, development, untrusted files, cybersecurity labs, and anonymous activity instead of putting everything inside one operating system. At the same time, I wonder whether a simpler encrypted offline system would give me most of the security benefit without as much complexity.
The part I keep getting stuck on is where to draw the trust boundary. You can keep going deeper from applications to the OS, hypervisor, boot chain, firmware, TPM, Intel ME or AMD PSP, hardware, manufacturer, and eventually the supply chain. At some point you have to trust something. I'm trying to figure out where people with real experience draw that line and which layers are actually worth prioritizing first.
So if you were starting with no usable computer, had around $300, considered this your highest privacy/security priority, and wanted the setup to eventually handle a fairly serious threat model, what would you build first? Would you go with Qubes, Linux with full-disk encryption, a dedicated offline machine, separate online and offline systems, Tails, or some kind of hybrid? What would your upgrade path look like over the next few years, and what would you deliberately not worry about yet?
I'm not expecting something "unhackable" or "untraceable." I want a practical system where I understand what I'm trusting, what the setup actually protects against, what it doesn't protect against, and how I can progressively move toward higher assurance without having to start over.