Debit cards: Is it ok to pay with a debit card occasionally while traveling abroad instead of a credit card? And how much money should I have on my debit card?

First, please be nice. I rarely travel and I’ve only traveled once out of the country 8 years ago and that time I was with my family.

I am traveling to Sweden, Denmark, and Norway in 2 days. I will be gone for 9 days. I have 2 credit cards: A Capitol One Savor card with no FTC and my bank’s credit card, but I am gonna try not to use that one because that one will have fees on it. I also recently got a Schwab debit card in case I need to withdrawal cash. However I’m now starting to think of the what ifs and if something goes wrong with my credit cards, like if they get declined or stop working or if I exceed my credit card limits (I hope that doesn’t happen but I don’t really have high limits, my Capitol One is like $3000 and my other bank card is $1300). I’m wondering if I should add more money to my debit card just in case I need to use for something other than withdrawing cash. I *know* it’s smarter and safer to use credit cards but is it ok if I use my debit occasionally to pay for something? I was planning on locking it on the Schwab app when I’m not using it to prevent purchases. So if I’m relying on my debit card more than I thought I would, approximately how much money should I have on my card for those destinations and for being gone that long?