On another note, it may make sense not to cash out your Swiss 2nd pillar prematurely, even if you could.
You could also invest and leave them on a vested benefits securities account in Switzerland, such as valuepension or VIAC (both not to be confused with 3rd pillar account products, even if they may effectively be run by the same people).
It will be more costly than managing them yourself as part your liquid assets, e.g. your IBKR account. But you may likely enjoy tax-free appreciation and compounding*. That is, not have to pay taxes on interest, distributions, wealth or capital gains (in cases of portfolio shifts).
Depending on the tax treatment and rates of Swiss 2nd pillar accounts in your case and country, that may be worth paying the higher fees for such products in Switzerland
* I would assume so at least for EU/EFTA countries, that harmonisation of social security and taxation will not have the account taxed before cashing out. Beware of other countries though, if you intend to keep things legal (worst case, they may consider it a taxable account as any other).