"Wins To Watch" refers to FIFA 23 Coins if the player's team wins three matches in their next eight domestic ties (starting the 30th of September) They will be awarded an additional one-time boost in stats similar to another in-form. So if Man City win 3/8 games, Haaland gets another +1 over and above any in-form updates He receives. (Lol 'if'.)
Nations to Watch means that every player with a Ones to Watch card whose country is participating with this year's World Cup will receive a one-off in-form upgrade if their team wins a match throughout the match. Tough times for Erling on this front, it seems, due to Norway's non-participation. ('Tough times for Erling' is not something we expect to write on many other occasions this year/decade/millennium.)
Even better, Nations to Watch players don't even have to be selected for their national team to be upgraded, meaning that even if Gabriel Jesus somehow doesn't make Brazil's squad and his team picks up victory in Qatar then the Arsenal striker will still receive an additional.
In the end, it's worth noting it is important to note that Ones to Watch players do not get upgrades based on other promo cards. So if Tyler Adams gets some sort of wild 90+ card in April , in the new promotion called Factsmashers or whatever you're looking at, your OTW is not upgraded as a result. (Sorry Tyler. If it helps you feel better, then you're in almost everyone's preorder OTW package.)
The unusual market for transfers of last year's pattern meant that it was sometimes practical and cost-effective to include good promotional players to your team, even within a few days after they came out. This could prove to be the case in FIFA 23, but for these days, the best Ones to Watch players are likely cost you a significant premium. Because they've been given no updates at all and are cheap FUT 23 Coins not receiving any upgrades, it's hard to recommend spending coins on them.