Can I add my own list of blocked or allowed websites?
Not yet. Skie blocks websites through the filtering DNS and Chrome's enforced safety rules, and you choose which filter a group uses, but custom per-website allow and block lists are not available today. The team is working on them. Until then the filter choice and the app list do most of the job.
Many admins ask for a box where they can paste a list of domains. Skie does not offer that yet. What it does offer is a locked filtering DNS on the device, so the filter applies on any Wi-Fi or mobile data, and a choice of filters curated by the owner.
Your organisation or a group can pick a different filter from the owner's list, and the group's choice overrides the organisation's. That gives you some range: a stricter filter for junior classes, a lighter one for staff. The default for an organisation without its own is CleanBrowsing Family.
The other lever is Chrome and the app list. Chrome can be off, restricted or allowed per group. If a site matters little, leaving Chrome off the list removes the browser entirely. More than fifty alternative browsers are always blocked, so a student cannot move to another browser to avoid a rule.
For a specific site you need blocked right now, the practical route is a stricter filter, or not allowing the browser for that group while you wait. Tell the team what you need, since requests shape what gets built, with no dates promised. A practical tip: record which sites teachers complain about for a term. A short evidence list helps you pick the right filter and tells us what would be useful. See web blocked domains and filter settings.