Replace SharePoint Lookups using Power Apps 

Hi Brett, I think you are referring to what we call in the trade a "cascade drop-down." This is where the value of the first drop-down, filters what you see in the second. For this you could use a data connection to a list (a table in Excel or a small SharePoint list for example), to hold the choices for the second drop-down, with a column that specifies values in the first drop-down it responds to or filters on. I haven't needed a cascade drop-down since my InfoPath days. I'll see if I can do a video on this for you.

Hi wowcolors, A collection is a way to grab data locally into your app. That means if for go offline (temporarily go through a tunnel or something) you can still see the data rather than lose the connection to it. If you want to learn more about creating connections try this link. There is a good guide to creating a connection to a SharePoint List. Link: blog.mydock365.com/a-basic-guide-to-creating-and-using-collections-in-powerapps

Add a SharePoint Choice column and allow for multiple choices (hidden in the advanced settings). This allows you to store multiple values using an array inside the Power Apps form immediately. You can manipulate multiple values in Power Apps, but you will need to learn how to work with JSON objects if you do not do so already.

Yes, Power Automate triggers on the "OnSave" event within the Form. This does not fire when you update a row in grid view. There are some ways to resolve this using SharePoint HTTP requests but they do not offer this as a trigger. There are some developers solving this in GitHub. Watch this space.

Do you know what licenses they provide to staff? Are they looking to review this in future? There are not many alternatives, without requirement of code, but I will keep looking and let you know, and do a video on it if it can help you.