Not unless your entire stack down to the bare silicon is also FLOSS, and the community is able to verify.
There is a lot of navel gazing in these comments about "the perfect solution", but we all know (or should know) that perfect is the enemy of good enough.
On Qubes OS (my daily driver), which runs everrything in VMs with strong, hardware virtualization, you can use minimal operating systems with very low number of installed libraries for security-critical actions: https://www.qubes-os.org/doc/templates/minimal/
There is a lot of navel gazing in these comments about "the perfect solution", but we all know (or should know) that perfect is the enemy of good enough.