Security of seeds and PIN review needed

For a seed phrase I would avoid seed.txt if you can. Plain text inside an encrypted vault is better than plain text alone, but it is still easy to accidentally open, index, back up, or leave in editor history. For small “spending” amounts, a paper/metal copy stored somewhere boring and safe is usually simpler. For password-manager backup, an encrypted export on an offline USB drive can be reasonable, but test restoring it once and keep the password/key separate from the drive.