Germany long term investing. ETFs vs private pension (pensionfriend or equivalent)

I'm trying to decide between continuing with my existing Deka ETF portfolio via Sparkasse or opening a private pension contract with Pensionfriend, and I'd appreciate some opinions from people who have looked at both/similar options.

My situation:

• Single, 30, employed in Germany
• Investment horizon: ~37 years
• Current ETF portfolio: ~€34,000
• Monthly investment: €1,700
• Currently investing through Sparkasse/Deka
• No plans to retire early

Current portfolio consists mainly of:

• Deka MSCI World ETF
• Deka S&P 500 ETF
• Deka EURO STOXX 50 ESG ETF
• Deka Euro Prime ESG ETF

I have already stopped new contributions to higher-cost active funds (GlobalChampions and Swisscanto) and am gradually simplifying toward ETFs.

What I'm trying to understand:

1. Is a Pensionfriend private pension (not Rürup) worth the additional annual fee (~0.69%+ETF TER, nothing else as far as I could tell) compared to holding ETFs directly?
2. How valuable is the tax benefit (12-year / age-62 rule, only half the gain taxable) in practice? This rule says that only 50% of the gains is taxable at the minimum of the capitals gains tax rate or the personal income tax rate. In contrast, for the ETFs, 70% of the gains is taxable at the capitals gains tax rate no matter what.
3. Does tax-free rebalancing inside the pension wrapper make a meaningful difference over a 30-40 year horizon, or is cash-flow rebalancing with new contributions sufficient?
4. For someone who mainly wants US and European equity exposure + the developed world, would you stay with a direct ETF depot or use a pension wrapper?
5. Has anyone here done a detailed calculation comparing: direct ETF investing (including Vorabpauschale and capital gains tax), and Pensionfriend after all fees and taxes?

I'm particularly interested in experiences from people who actually switched from a normal ETF depot to Pensionfriend or equivalent (or decided against it after doing the math).