You could create your own server action for the bulk import, here an sample on how to do it with nodejs:
var fs = require('fs')
var { Pool } = require('pg')
var copyFrom = require('pg-copy-streams').from
var pool = new Pool()
pool.connect(function (err, client, done) {
var stream = client.query(copyFrom('COPY my_table FROM STDIN'))
var fileStream = fs.createReadStream('some_file.tsv')
fileStream.on('error', done)
stream.on('error', done)
stream.on('finish', done)
fileStream.pipe(stream)
})