With FTC we used to have the ability to add some javascript to our custom actions (ribbon) in order to programmatically enable or not actions. Right not this is not possible anymore when having custom actions from provider hosted add-ins because of security concerns. I understand you don't want custom third party JS to run under SharePoint's context for reliability/security concerns.
It'd be great if we could provide an endpoint that SharePoint could ping to know if the button should be enabled or not in the ribbon

There are a handful of PnP Provisioning service pre-requisites that are required (tenant level permissions, app catalog, access to app catalog, etc) to deploy the Custom Learning and Starter Kit template successfully. We also know that users miss our documentation. Hence this request is to harden the PnP Provisioning service deployment process to clearly call out provisioning failures specific to not following pre-reqs and to point users to that documentation.

We have a solution which provisions lists to several site collections. There can be different language version, so list display names are localized. It would be nice have a REST endpoint to retrieve list by it's internal name.

I am sorry if this duplicate or if I missed to read the documentation. I tried to toggle allow list deletion to true or false and couldn't find the property.

I have implemented, JSlink for the Document library's default view, where JSLink associated at field level to get field properties and invoke Java script functions to get the properties and do some tweaks.

We want to have same type of approach with the Modern view also. As per Microsoft still it not supported in Modern view of library. Any alternate way to achieve this?

I have already tried with the custom Action at the document library Toolbar (associate custom action with Content type), but the issue is it not support JavaScript calling.

It's 2017, you really shouldn't be using <table> for layout!

SharePoint should use Grid and Flexbox for layout of not just the Ribbon, sidebar, navbar etc but for List forms too. This would clean up the SharePoint HTML and CSS considerably as well as making it easier to customise the layout of forms.

(Sure, there's an argument to be made that there's a semantic relationship between form input and tabular data, but I'm pretty sure the 'tables for form layout' is just something carried over from earlier versions of SharePoint needing to serve browsers with poor standards support.)