OP, blockchain is a digital ledger and since the technology draws its power from the peers—or nodes—on its network to verify, process, and record all transactions across the system. This ledger is never stored, but rather exists on the “chain” supported by millions of nodes simultaneously. Through encryption and decentralization, blockchain’s database of transactions is incorruptible, and each record is easily verifiable. The network cannot be taken down or influenced by a single party because it doesn’t exist in one place.
Blockchain technology provides a platform for creating a highly secure, decentralized, anonymized, yet auditable chain of record, used presently in cryptocurrency systems. this same technology could also be used to record and report votes and prevent many types of voter fraud in elections.
Since Blockchain deals with a digital ledger that is saved on the chain, it can not be edited or stored in the office of the government body in charge. So true security is sure that all data from the vote can be store on chain and can't be tempered with. Its transparency means anyone can track the record. In terms of security, it also means individuals can stay at home and send out their vote without going out and facing violence in the election scene, because in some countries there is usually violence in the election scene.
is that type of voting tested or implemented anywhere?
Yes, Sierra Leone and Moscow has.
Sierra Leone conducted a Blockchain-based voting system on March 7 and became the first country to become so. Leonardo Gammar of Agora, stored votes in an immutable distributed ledger, thereby offering instant access to the election results.
Authorities of Moscow planned and launched a blockchain-based electronic voting system pilot project in June 2019. The project was carried out by partnering with the Moscow City Election Commission and Moscow Department of Information Technology (DIT). They provided the required support for the testing of the project.
https://www.blockchain-council.org/blockchain/top-countries-that-conducted-elections-on-the-blockchain/
https://www.investopedia.com/news/how-blockchain-technology-can-prevent-voter-fraud/