First off, this is my very first post so apologies if it's not the way to do it but the company I work for- Elastic- has made a number of their on demand courses free. They're typically fundamental courses so great for those just getting started and include things like SIEM and Observability (logging, APM, metrics- infrastructure monitoring).
The underlying tech is open source Elasticsearch and is one of the top repositories on Github, powering so many of the sites and services you use everyday without even knowing it- for searching, centralising logs and improving security postures. Anyway, even though I work for them, I've seen the impact the tech is making and the prevalence of it amongst nearly every organisation so hoping this helps upskill anyone looking for work or just interested in learning new things to help their career or build something neat.
Good luck and all the best!
(Thanks for all the nice comments to everyone already, much appreciated and glad it's helping a few! These courses were originally $200 USD each, can't say if they'll stay free forever but give it a shot and reach out if you run into any issues)