Given the current technical possibilities for surveillence, I think IF a powerful organisation or government does want to spy on someone or a company, they have plenty of tools available.
One tech that comes to mind, which seemed pretty mind boggling to me at the time (already a few years old), is a special video-analyzing software that can be used to analize micro-vibrations on surfaces of objects to reconstruct the sound emitted to create these vibrations.
I guess it depends on the quality of the video, however as technology advances these limitations will also be less and less of an obstacle.
Every case is very individual. If you live in third countries, in small cities or towns, or in poor villages, you can definitely feel very safe in terms of spying. It's very individual, if one knows the undeveloped/developing country well, he/she can manage the situation very well. There are countries where police isn't advanced, lacks knowledge, equipment and athletism and so on.
However, to the best of my knowledge, officially backdoored CPUs don't have (enough) persistent, read- and writeable storage on die to allow for such an attack. Furthermore, anyone with the amount of resources to set up such an attack, usually aims for other goals than stealing some BTC.
If you want to be extra paranoid though, just unplug any other secondary storage before booting Tails and fully turn off the device after creating the seed and remove all power (to flush dynamic memories).
For the maximum level of paranoia, simply never reconnect the hardware to the internet, at all. Keep it as a forever-offline signing-only Tails PC.
To avoid doubts, better use an old computer or a hardware wallet (made with open source software and hardware)
You will be much better off with an open-source, open hardware, airgapped hardware wallet.
I can't believe that nobody is really criticizing this 'old computer' idea. Your 15-16 year old PC will most likely run outdated OS and / or packages, which are much more likely to be exploited than bugs in the CPU.
It's a very different what's official and what's unofficial. I'm really afraid that when I buy a very expensive CPU, it may come with another surprise. What if every CPU since 2012 comes with secret nano microphone that doesn't need internet and uses radio frequencies to transmit data? Does it sound sci-fi? Probably, but doesn't mean that I am crazy and out of mind. There is a possibility that what I said is a real threat.
But it's my personal opinion that old CPUs can be safer. The reason why I think so is that there was a time in technology that the development was more important than spying. Now, things are pretty developed and monetized, it's time to make some powerful things more affordable, spy on people and control them.
I think we need to group together and find a way to stop the governments from doing this to us. They cannot be allowed to permit such spying to be possible in the first place. Laws are supposed to protect our freedoms, not exploit them.
Although I also think that private companies would not want to miss out on customers, if they make such devious devices in the first place. Perhaps the free market will take care of the problem?
You can't imagine how many people like the idea of everything being controlled by the government. There are a lot of people who like the idea of government controlling your messages, transactions, your footsteps, etc. You can't make an independent person out of slave.
For maximum individual cyber security, you have to do a big research and choose a different country to live in. You have to choose a specific country, specific city, specific street, specific neighborhood, change your personality and openness, absolutely everything matters.