I've used the search feature on this forum but didn't have much luck.Are there any US investors, hard money lenders, or groups that invest in flips outside of the United States, specifically in Europe (Netherlands, Spain, etc.)?

I think you'd find it very helpful in your situation.

I'm eager to learn more about:Identifying undervalued properties: Are there any specific strategies or resources you recommend for finding deals below market value?

My strategy incorporates asset protection measures like LLCs, specific trusts as well as professional property management to spread risk and ensure quality operations.As well as using tax codes to my benfiitSection 179, IRC Section 162, Cost Segregation and Bonus Depreciation and later 1031 them out for larger projects. 

JoelIt seems to cater specifically to agents. 

You CAN limit that agreement to a specific property; but, as others have stated, agents are looking for a certain amount of loyalty from their clients.If an agent gets vibes from a prospective client that indicates that they want to cheapskate and not pay a professional for their service, they are not likely to waste their time with them.

@Derick Jennings Without knowing more about your situation, I'd likely recommend a house hack, a strategy I wish I would have known about when I got started.

I wanted to be absolutely sure I had complete agency and that I knew how to perform my own analysis over various situations.

@Jaycee Greene is pointing out that we need to be specific when we are planning to meet with people.

LTRs do not face those types of situations.