Converting generator power to "clean" power for sensitive electronics

I have a Duromax "Beast" power generator that I’ve been using to run my home during power outages due to storms, etc. From the start, I decided to do things right and had an electrician install an input outlet with a manual transfer switch onto an exterior breaker panel which feeds the house; a high-quality cable runs power from the generator into the panel.

We had a recent hurricane and once I figured things out, the generator ran things near-flawlessly. However, in researching generators, I read about sine waves and how generators supply "dirty" power, so I was worried about using any sensitive electronics — TVs, computers, cell phone chargers, cable modem, etc: we unplugged every single one of those things and didn’t use them.

I have a relative who is an electrician, and he argues that if I have decent surge protectors on those outlets, then all of those sensitive electronics should be absolutely fine, and this is echoed somewhat on a couple of sites where I’ve been researching this issue. However, someone else argued what I was thinking: surge protectors guard against spikes in power, not sudden drops or brief spans of low power…and those could possibly damage sensitive electronics as well.

Which of us is correct? Am I being overly worried and good surge protectors are truly all I need? Or is that honestly just a makeshift measure and there are better solutions? Which one is likely to be the most effective…and economical?

Thank you in advance for all of your advice!