According to levels.fyi (if we assume its unbiased) a median dev income is around $82k in Germany vs $168k in the United States. Let's assume the mean is near that as I can't find any stats on median CoL. Also Let's compare two MCOL(?) hip cities: Portland OR and Leipzig.
$82k is $4.1k take home (with healthcare) as a single in Germany.
$168k is $8.8k take home as a single in Portland.
Let's say monthly expenses are $1.5k as a single in Leipzig. According to numbeo I would need $2.5k for the same standard in Portland.
So in Portland I can save $6.3k or 2.5x my expenses and in Leipzig I can save $2.6k or 1.6x my expenses.
Healthcare is included in the net pay for Leipzig, but not Portland. Employer 401k contributions and other benefits are also not considered.
Other things to consider are safety, unemployment, workers rights, tenant rights, quality of healthcare, cost of elderly care, government retirement plans, PTO, sick leave, maternity and paternity leave, cost of childcare, etc.
Really comes down to what's important to you IMO.