Before discovering Monzo I used the crowd swap prepay card WeSwap. Like Monzo there are no transaction fees for payments, though you do need to swap currency which incurs a small fee.
The limitations is the fee to take any unused funds out of your account when you return home. I’ve just used my WeSwap card to top up my Monzo account, using an amount that I’d changed into £.
I’d be interested to know if other people have tried moving WeSwap funds from another currency onto Monzo - this would save both the conversion fee and the cash withdrawal fee.
I would never use a credit card to top up Monzo but if you have prepay cards this might be a good way to consolidate any funds.