I have a new assignment from 1st October in UK, whilebut I am living in Germany now. I have a new assignment from 1st October in UK, but I am living in Germany now.

Two options: "I have a new assignment from 1st October in UK, but I am living in Germany now." Correct, but very slightly strange sounding. "While I am living in Germany now, I have a new assignment from 1st October in UK." Flows more naturally, especially because it is now in chronological order.

Last week, I visited London and dsecidured my new flat, making a preliminary contract with a real estate agent. Last week, I visited London and secured my new flat, making a preliminary contract with a real estate agent.

That’s why I transferred the money from my bank account with a German local bank by using the Wise App. That’s why I transferred money from my bank account with a German local bank by using the Wise App.

Making severalWith just a few taps, I could smoothly transfer the money to the real estate agent. With just a few taps, I could smoothly transfer the money to the real estate agent.

If you want to emphasise how quick and easy it was, "with just a few taps" works nicely.

It’s a really amazing experience of fintech app experience. It’s a really amazing fintech app experience.

Or: "It's a really amazing example of fintech."