[Exodus16]

"Practical unity, for a start, is about people leaving their denominations and meeting on the basis of locality."
Nope. Practical and unity are both basic English words that have meaning.
By putting a requirement on believers (leaving their denominations) this concept becomes a "get out of jail free card" there is no need for those who are on the proper ground to reach out to other believers in any real/practical way.
in this thread there are many high sounding words that don't match what we have observed now and in the past regarding the LCs being one with the believers all around them.
Here are some practical examples of unity of saints that began ecumenically
- at the end of the block where I lived in high school one meeting hall was shared by Seven Day Adventist and another Sunday meeting group. This arrangement seemed comical but they made it work as both sides could see "he who is not against us is for us"
- in a Methodist joint in the country the pastor was dying of cancer, nearby denominations joined them in prayer, sent food and flowers and even picked up the burdens (the pastor had been arranging donations for delivery - the members of other denominations filled the need.)
- two moms met at their kids baseball games prayed for one another and each other's families (was the ground of their unity was Christ or the baseball diamond?)
These are practical examples. I can see them and point to it. Even if the saints involved don't have the teaching or the words, they look around them and act as one with other saints around them. Contrast this with the LSM who have all these high sounding teachings but have no real care for those around them who do not follow Christ in their prescribed method. This is observable.