This prompted me to search "banana beer", and apparently in some East-African countries there are beers where banana is the main ingredient in the actual mash.

My favorite beer - Live Oak Hefeweizen - has natural banana notes in it. It seems that’s common for Hefes, anyway.

I’d be curious as to how the bananaweizen tastes and whether it ruins the beer - like a Radler in Britain or Blue Moon which kinda tastes a bit artificial.

I posted in another comment about micheladas, but I think why I make a distinction about that not ruining the beer is due to the complexity of the flavor.

The yeasts used for hefe’s quite often produce banana ester. Many/most yeasts do at certain temperatures and it’s considered an ‘off’ flavour in most styles, but desired in some white beers.

Beer and banana mix pretty well surprisingly.

Radler (beer with some lemonade in it) is also pretty common in Germany, with a similar reputation to what you describe.

Bananaweizen blew my mind because it was the first time I learned banana juice existed. There are other wheat beer mixes, and there is the whole 'radler' thing too