It's been a couple of years since we started seeing phones with foldable displays, but the only company that has really left an impression on most people is Samsung with its Z Fold and Z Flip lines. Huawei has made a few foldables by now, and yesterday it announced the Mate X2, but you don't get Google services with those.
If you've been waiting for other companies to introduce alternatives, a new report from The Elec (via SamMobile) may have some good news for you. According to the report, Samsung's display division has been developing foldable display panels - specifically the kind where the display bends inward, similar to Samsung's own phones - to sell to Google, Xiaomi, and OPPO.
All three of the companies have either shown off foldable prototypes of their own or been reported to be working on a phone with the form factor, so this seems to make sense. Rumors of a foldable Pixel device first popped up last summer, and today's report claims that Google is sourcing a 7.6-inch display from Samsung Display. There's no information on a potential external display, though it could be sourced from a different company.
OPPO, for its part, is reportedly getting a 7.7-inch display, but it comes with the interesting tidbit that it's more of a clamshell-type display, similar to that of the Galaxy Z Flip, albeit significantly bigger (the Z Flip has a 6.7-inch panel). Additionally, OPPO is looking for an external display that's between 1.5 and 2 inches in size, which would be between the display on the Z Flip and Motorola's razr in terms of size.
Finally, Xiaomi is sourcing an 8.03-inch foldable panel from Samsung and another display supplier, CSOT. An external 6.83-inch panel is also mentioned, so it's more like the Galaxy Z Fold2. Last year, Xiaomi had an external folding display prototype instead, and it even had two folds allowing the full display to be even bigger. It seems that inner displays are becoming more prevalent, likely due to them being more protected when not in use.
All of these phones are said to be releasing within the year, so we shouldn't have long to wait to learn about them, assuming plans don't fall through.