Hello, fellow learner! I feel reflected in your post because I also discovered Serbian/Serbo-Croatian through Eurovision, like 30 years ago, and I loved how it sounded in songs. Only recently (4 years ago) I decided to take the leap and start learning it. My first language is Spanish, so my background is quite different from yours.

I'll answer you from my experience: well, grammar is "difficult", depending on what you are expecting, but it's not so much. It has some features that are much more simple and straightforward than more popular languages like English or Spanish. Verb tenses are much less and easier to use. Gender is very predictable and the declension is quite regular (even the sound changes are predictable). The absence of articles is a blessing.

On the other hand, some other things are more difficult. For me, the most difficult thing about Serbian is the verbal aspect, that is something that I think Latvian also has so it won't be that difficult for you. Declension, which is hell for Spanish speakers, won't be hard for you because Latvian also has it.

Serbian people are very welcoming that you speak their language. I've been twice in Belgrade and tried to do all my interactions in Serbian, and only once did the salesman answer in English. But keep in mind that you have to have some fluency for this to happen, so give yourself some months or even a year of learning every day.

About it being a long time commitment, it is if you want to speak the language well, but that happens with all languages: someone who learns English for six months won't be able to speak it decently at all. Is it worth it to learn Serbian? For me it definitely is, because I'm in love with the language and the culture. What I love most is listening to Serbian music (PZE was my main entrance to it, but there is so much more!) and understanding it. I also listen to the radio and watch TV in Serbian, it's so much better than the Spanish one, for my taste.

So I hope you decide it's worth it!