Tides are a really important factor to many windsurfers. They dictate the conditions and help our decisions on where and when to sail, so it goes hand in hand with the wind forecast.
Your beta is a bit confusing and not very accurate either, at least not for where I live which is on the UK south coast - we have an abundance of live tide apps here to use. As they work with what are essentially only predictions they are suprisingly all consistent and accurate.
I've worked with some API's to these tide tables, many are free or pretty cheap so I think to add tides to Windy is not a big issue, it just depends on who you ultimately use for the data source(s), how many days in advance you want to predict and how much if anything you want to pay.
Figures and graphs are great, plenty of apps to reearch ideas for the UI.
Single app for wind and tides is a winner !