Google Trends is not really an indication of how well a particular camera brand or model is doing, but since I already see misleading information online, here are some Google Trends comparisons:
Sony a7r3 vs. Nikon D850 (no surprise here, we already knew that the D850 outsold the a7R3):
Sony vs. Nikon vs. Canon – for any “meaningful” (not really meaningful at all if you ask me) camera comparison between brands, you need to add “camera” in the search term, otherwise you will get all Sony TVs and Canon printers in the mix (even this is still not accurate because of the Sony and Canon video cameras that are included in the search terms):
