I have a sort of plan (not yet followed) of getting a 2nd citizenship in another country, most likely the UK or Ireland.
For that I would probably need to work as a sponsored employee for 5-6 years, but there are certain visas and tricks that can lessen that. E.g. it's not often mentioned that the UK Skilled Worker visa technically doesn't require full-time work, so one could at least "semi-retire" on a part-time job while working toward the UK citizenship.
Once I have the 2nd citizenship, I would switch between the two countries/regions, spending longer stretches of time in each citizenship country and shorter stints in nearby countries.
E.g.
9 months UK, 3 months Switzerland
9 months Australia, 3 months New Zealand
9 months UK, 3 months Spain
9 months Australia, 3 months Hawaii
The main benefit of this approach is that it allows a longer "stable" period to be spent within a region (e.g. the UK). This can allow for cheaper accommodation, some short-term employment to top up savings, and generally a slower pace of travel. All of which seems to be in harmony with ERE philosophy.
I like to think each citizenship "unlocks" a chunk of the planet Earth for slow & steady exploration.
That said, I'm nowhere near beginning this. Partly because I'm still on the accumulation treadmill and can't seem to figure out when enough will be enough, in terms of savings & investments. But that's a personal problem with my own mindset, not a weakness of the strategy.