UA is a derived metric: all follow broadcasts (currently ~ 150 million, on average currently every second about 2 follow transactions are added to that total) are available to fetch from the blockchain, but computation results of every account's UA score are not. Please keep in mind that with every (un-)follow transaction from user A to B, all UA scores of every account change (slightly).
Base message: UA is highly dynamic and extremely computation-heavy. As to running client-side, the question is what actually would run on the client. The fetching of JSON-i-fied UA end result scores from our API is possible. Calculating UA scores done live and client-side from raw blockchain data and/or a follow DB is not feasible at the moment.
If you like to tinker around with UA yourself, you might want to have a look at my original UA article which includes UA's core algorithm (more sub-algos are included currently, to properly deal with dangling nodes and sybils), an example graph (of 6 nodes, 13 follows), and the computation results of that example graph. It's a fun exercise!
Hey, I would love to talk with you on Discord about implementing UA into the 1UP platform.