The more you train for and learn the better, I would also recommend looking into the Linux Foundation - https://training.linuxfoundation.org/certification and the very well known Linux Certifications from Redhat - https://www.redhat.com/en/services/certification since they are performance based and you cannot pass them without actually being able to do the work.

If you want to add a few more in demand skill sets to the mix I would also recommend getting at least a CCNA (Cisco Certified Network Associate) and possibly a CCNP (Cisco Certified Network Professional) certification so you will also be very sufficient in understanding and configuring routers and switches for LANs and WANs. These would help when determining how to scale your website, if you ever end up managing a colocation setup or have to get hands on with the hardware as there is normally not a separate network engineer on site unless the customer has a very large budget to pay for both system engineers and network engineers.