You mentioned you wanted compound interest effect, and tax free growth. The best answer for this is to use a pension vehicle. That is the closest way to have you cake and eat it, but you also encounter the pension vehicle charges.
If you can't do this in a pension, there are several DIY options. Remember that stocks give you the return via dividends, and price increase, and different options tax these two differently.
IIUC, Even if you can could buy a US domiciled ETF, they are all forced to distribute dividends at least annually, which would be taxable at your marginal rate, and these dividends will have a withholding tax already applied. And you would need to re-invest these dividends in order to get your full compounding effect. So you would get tax free growth on the 'price' of the share, but annual tax on the dividend.
If you buy a distributing eu domiciled etf you will get annual tax on the dividend, and 8 year tax on the 'price'
If You buy an eu domiciled accumulating fund, you would only pay tax on the dividends and capital growth at every 8 year anniversary of your purchase (the dividends and the price increase are all rolled up into the 'price' of an accumulating etf), i.e. you get tax free growth for 8 years. And you would get 'auto' re-investment of any of the dividends.
You could also buy a large set of shares directly, you would get tax free growth on price, and annual tax on dividends, but a lot of paperwork...
Which regime gives you the best return depends o the future tax rate, and the future distribution of returns via dividends or capital growth.
Note Marc was one of the first on aam to point out a few years ago, that there are US estate tax dues if you are holding US equity above a certain value when you die.