While SQL Sentry supports monitoring SQL Server on Linux, it only works in "Limited" mode and doesn't support monitoring operating-system-level metrics such as CPU utilization, memory, disk latency, etc.
SQL Server on Linux is slowly but steadily gaining more and more traction, and it's reasonable to assume that it would be significantly popular in the future, due to cost savings and improved performance.
It should be technically possible to remotely monitor Linux systems, even from within a Windows machine.
We'd appreciate it if we could improve our offering as a SQL Sentry MSP and expand our capabilities for customers that have SQL Server on Linux as well.
Thanks!