Disclaimer: this is going to be a bit of a long question, so bear with me.
I've heard people claim that the purpose of the gift of tongues is to preach the gospel to foreigners in their own native languages. People who hold this view commonly cite Acts 2 as their biblical basis:
3 And tongues that looked like fire appeared to them, distributing themselves, and a tongue rested on each one of them. 4 And they were all filled with the Holy Spirit and began to speak with different tongues, as the Spirit was giving them the ability to speak out.
5 Now there were Jews residing in Jerusalem, devout men from every nation under heaven. 6 And when this sound occurred, the crowd came together and they were bewildered, because each one of them was hearing them speak in his own language. 7 They were amazed and astonished, saying, “Why, are not all these who are speaking Galileans? 8 And how is it that we each hear them in our own language to which we were born? 9 Parthians, Medes, and Elamites, and residents of Mesopotamia, Judea, and Cappadocia, Pontus and Asia, 10 Phrygia and Pamphylia, Egypt and the parts of Libya around Cyrene, and visitors from Rome, both Jews and proselytes, 11 Cretans and Arabs—we hear them speaking in our own tongues of the mighty deeds of God.” 12 And they all continued in amazement and great perplexity, saying to one another, “What does this mean?” 13 But others were jeering and saying, “They are full of sweet wine!”
[Acts 2:3-13 NASB]
Now, without invoking Acts 10 just yet (I'll do in a second), notice that Acts 2:3-13 never mentions the words "preach" nor "gospel", nor gives the impression that they were preaching. We are only told that they were speaking "the mighty deeds of God" (V11) and that many took it as a joke and said "They are full of wine" (V13). If that's preaching, it's not a very effective one.
Rather, the real preaching began immediately after with Peter's sermon (Acts 2:14-42), when Peter raised his voice and spoke to the whole multitude, and thousands converted to Christ. The tongue speaking that happened before was just the warmup to catch people's attention.
That said, now let's jump forward to Acts 10:44-48, when Peter is in Cornelius's house preaching to him and his household:
44 While Peter was still speaking these words, the Holy Spirit fell upon all those who were listening to the message. 45 All the Jewish believers who came with Peter were amazed, because the gift of the Holy Spirit had also been poured out on the Gentiles. 46 For they were hearing them speaking with tongues and exalting God. Then Peter responded, 47 “Surely no one can refuse the water for these to be baptized, who have received the Holy Spirit just as we did, can he?” 48 And he ordered them to be baptized in the name of Jesus Christ. Then they asked him to stay on for a few days.
[Acts 10:44-48 NASB]
Notice that Peter is astonished because he realizes that Cornelius and his household, despite being Gentiles, just had the same miraculous experience they had had at Pentecost in Acts 2. But here is the key point: when Cornelius and his household spoke in tongues, what did they say? Were they preaching to foreigners? Was Cornelius preaching the gospel to Peter? Of course not. Rather, V46 is very clear that they were exalting God. In other words, they were praising/worshiping God in tongues, the content was directed at God, not at foreigners (they were inside a house).
Question: in light of Acts 10, where the gift of tongues was clearly used for praising/exalting God, and acknowledging that Acts 10 and Acts 2 present the exact same experience, can we conclude that Acts 2 is an instance of "praising God in tongues" rather than "preaching the gospel to foreigners in tongues"?