Learn Russian: Умные гаджеты становятся всё более популярными. - Smart gadgets are becoming increasingly popular.

The verb становиться (to become) requires the adjective or noun that describes what the subject is becoming to be in the instrumental case. Because гаджеты is plural, the adjective takes the plural instrumental ending -ыми.

What is the role of всё in the phrase всё более? Doesn't всё usually mean 'everything' or 'always'?

When placed directly before a comparative word like более (more), всё acts as an intensifier meaning 'increasingly' or 'more and more'. Therefore, всё более популярными smoothly translates to 'increasingly popular'.

Could I just say становятся популярнее instead of using более?

Yes! становятся популярнее is perfectly natural. However, using всё более популярными sounds slightly more formal and emphasizes the ongoing nature of the trend. Note an important grammar difference: when you use более, the adjective must agree in case (instrumental популярными), but the short comparative word популярнее never changes its ending.

Is гаджеты treated as a standard Russian word here?