To start with linux you can buy a cheap laptop (200 / 300 usd) and flash linux into it, then, once you can afford it, you can buy a Pc with Intel ME disabled, and without microphone , wifi, bluethoot and camera, form system76, novacustom PC, or nitrokey.... Best option for your security and privacy
Discussion
never heard of nitro key but i do use yubi key . Do you have any link for backing up these hw keys, my assumption is yubikey is backed up by yubi key only . When you scan the code to get 2FA enable , scan again with another yubi key to create a backup. This way if one fail then you have another. Dont know if another better way exist. nostr:npub1gxsss485j5yvwe7yffp48ddxr7qhshmzl9f8fvzrphltaj5zqaps8xkyrv or yes you can have any brand to backup