Assalamualaikum wa rahmatullahi wa barakatuh,
To be honest none here will ever know the answer, only Allah aza wa jal knows what is hidden in the hearts of mankind.
1. In Islam we are encouraged to marry right away but I understand that you have a desire to meet your potential spouse and see him in person and have a discussion with a mahrim present, this is all fine as per Islam, but if he wants to get married before meeting you in person, that is also fine in Islam as he has already seen your picture, spoken with you, etc. However, he cannot force you to marry him, you can meet him first and then decide for yourself.
2. With regards to foreign countries you have no information about, you should not travel to said countries without a male mahrim capable of defending you, especially due to kidnappings of women in these countries you never know. Hence it is obligatory in Islam, if you travel a certain distance, that you have a male mahrim accompany you to protect you.
3. The Prophet Muhammad (s) told us to marry based on faith in Allah and good character. Marriages don't last unless both spouses have good character. And faith in Allah is the primary reason we Muslims get married due to the huge reward that comes from marriage as the Prophet (s) stated that marriage is half of faith.
We want to marry someone who is better than us in our deen and encourages us to do good and forbids us from evil. That is because Allah says in the Noble Quran that he will unite Muslim families together in Jannah, that means, if your spouse is raised higher than you, then you will be raised to his level even if you didn't earn it. Hence we marry the opposite gender, a Muslim who will give us the best in the hereafter.
So you best know if this man is a good Muslim, has he ever encouraged you to do good deeds such as prayer, fasting, reading Quran, etc? Allahu alim, have you ever encouraged him to do good deeds such as growing the Islamic beard, jihad, gaining knowledge, etc? Allahu alim. It goes both ways.
4. With that said, you should recite ayat 25:74 in the Noble Quran, as it is dua for marriage. You can always pray salatul isthiqarah if you ever need Allah's guidance in making a decision like this. If you want to meet him again, bring a male mahrim with you and decide if he is a good believer in Allah, if he is, then I recommend marrying him, don't assume he's only interested in you for citizenship unless there is evidence of this, this may just be shaytan creating doubts in you to prevent an amazing good deed such as marriage.
What I know is, if he's a good Muslim, if he prays in the masjid frequently, encourages good, has the Islamic beard for example, constantly reminds you of Allah, then I don't think he'd be after citizenship. If he's the type of person who casually practices Islam, drinks alcohol, prioritizes wealth even in haram situations, etc; then he may be after citizenship, Allahu alim.