@Paolo, here are a couple of things you can think about:
„Pension plan“ means a couple of things. First, there are saving plans where the government pays you a contribution. They are labeled „Riester“. What product one can get under the „Riester“ label is very divers. From traditional insurance plans, to savings builder accounts, to fonds and ETF portfolios. Each of them might have benefits depending on your personal situation. Riester contracts are available for employees, not business owners (I am generalizing a little, it’s more complex, but true for most people.)
Then you’ve got all kinds of „pension plans“ without state contribution, and their idea is that they invest in higher interest/higher risk investments during the savings period and shift towards more secure/lower interest investments when coming closer to retirement.
A typical employee in Germany might decide to sign up for a Riester product to profit from the contributions, but not to pay every penny into it, just enough to maximize the contributions. And additional money then might go into an ETF portfolio, life insurance, and so on.
Here’s an example for an ETF based strategy: Qurion provides ETF portfolios for both purposes, investing and saving for retirement, and they show here how the strategy differs between those portfolios. (I just picked Quirion because they explain it well and they offer portfolios that are focused on sustainability or meant for retirement – so I think it’s a good starting point to look at the differences, but there are many others.)
So if you don’t mind the extra effort, you could plan your individual strategy similar to what Qurion is doing: invest in a sustainable ETF portfolio where the ETFs are in line with your idea of sustainability and switch to a different strategy like the one Quirion calls „Altersvorsorge“ when you get closer to retirement. Assuming retirement isn’t around the corner for you, I can imagine many providers, including Tomorrow, coming up with more sustainable offerings in the future that might be appealing when it’s time to switch strategies.