That's...highly debatable.
You're definitely right in some areas - methane leakages are reasonably cheap and easy to deal with (see the issue of abandoned oil wells for instance), and yes, giving up flying wouldn't be the worst sacrifice in the world comparatively. Similarly, a lot of farmland could be spared if less meat was consumed, but given how meat consumption is going up across the world, that doesn't look likely. I'd point to artificial meat, but recently there's been claims that artificial meat is worse for the environment because of its power requirements, so yay...
But as to the idea of the shift being completely painless? Debatable. Very debatable. Some claim that's true, some claim it isn't, and it certainly isn't just "propaganda" for saying it isn't. For starters, there isn't enough time to shift to nuclear in any meaningful way - definitely keep nuclear plants where they're still operating (looking at you, Germany!), but replacing fossil fuels with fission isn't going to happen in a practical time scale, and it's even debatable as to whether there's enough uranium to do so (a stat I recall reading is that if the world was powered exclusively by nuclear, we'd run out in 3 years, though I'm skeptical that's the case for a variety of reasons).
As for transitioning into renewables, again, debatable. I'll give you the credit of assuming you're already aware of the issues of intermitancy, battery storage, etc., so while it's certainly concievable that renewables could power things, but even then, the renewables debate tends to focus on electricity. Factor in stuff like industry and transport, and things get less rosy.
But even
that doesn't go into issues of consumption. We can debate degrowth if we want (read plenty of for and against articles), but I'll put it this way - if we assume that the only way to deal with climate change is lowering consumption, then that means lowering consumption of everything. Smaller houses, smaller (if any) cars, smaller earnings, etc. Basically, less of everything, or at least, less of what could be called luxuries - Meiam is likely wrong about healthcare (as that's compartively less resource intensive), but certainly right about stuff like cars and meat. Which runs into a problem, because getting people to accept less isn't a winning strategy. Every time standards of living have dropped, it hasn't gone well for the society in question.
Basically, there's no simple answers, and I'm skeptical of anyone saying there are.