Converting generator power to "clean" power for sensitive electronics
This is a half answer, based on some parallel knowledge not directly related to small home generators, so bear with me…
The only generators I get near are those on movie sets, which are gigantic by comparison - see Aggreko for an idea of the sizes I'm talking about. These, of course, are smooth as silk so require considerably less external mitigation.
Basically, you need several levels of protection if these are not already built-in to your generator.
Power limiting - ie surge protection.
Brownout - power slump - protection.
Grounding protection &amp; isolation.
Delicate electronics don't like any of those. A general purpose mains surge protector will be the least likely to come into play in this, but shouldn't be skipped; they're dirt cheap. The other two could be more insidious.
A UPS (uninterruptible power supply) is the standard method of protecting computers &amp; other delicate electronics from brownout or even total power-loss. These are an entire topic to themselves, but start fairly cheap &amp; run to 'ouch' prices.
Grounding protection/isolation may be built into these - pay more, get more. Essentially, grounding protection is built on the 'in-house' side of a 1:1 coil-wound transformer. These seemingly odd little boxes - 120v in, 120v out, (or 240v i/o as appropriate) seem to do nothing; but they isolate one circuit from another. You then correctly ground the 'in-house' circuit to achieve total isolation from the external power supply.