The PragProg folks have a new book that includes exercises and looks very promising as an introductory material. It's available in beta state and apparently about to be finished: https://pragprog.com/titles/nmquantum/
It took me years to notice a flaw in this approach: it's based in the premise that everyone has time for side projects.
From that point I think about it as a bias. Nowadays I try to assess if the candidates with no public activity on GH and no side projects have the passion and interest I look for, but can't take it further outside of work due to their specific circumstances.
"On Tuesday June 9th 2020 Heroku changed the certificate used for terminating TLS for built-in <appname>.herokuapp.com hostnames from a certificate issued by DigiCert to one issued by Starfield/AWS. This change was rolled back on June 10th because a small subset of Heroku customers had pinned apps to the DigiCert certificate or had apps that could not establish a chain of trust with the new certificate for other reasons.
A new DigiCert-signed certificate will replace the current one before June 22nd (when it expires)."
If you're taking care of most/all the technical details, the only blocker that would prevent me from this kind of service is the unknown legal/compliance work I'd need to do in order to start taking this kind of money and have access to those users' data - is that something you can provide guidance on?
I can't recommend enough watching the The Salt of the Earth[0] documentary. It's not only an impactful review of Salgado's career but also a great (and visual) way to expand our knowledge about the world and its recent history.
I live in Spain, outside of those two hubs but always keep an eye on them. Both have healthy dev communities that organize monthly meetups and conferences where it's easy to connect with local startups. Lots of open opportunities, often open to foreign folks, and at least a few companies with very strong technical teams. Salaries aren't near the SF range but should allow you to afford a healthy work/life balance and enjoy your time here.