How do you get started farming edible swiftlet nests? Does it need to be at the seaside? Do the birds need a particular environment, or just anywhere?

^^^
You need to set up in a place the species already inhabit in good numbers, and then attract them to nest in your "house".
They feed on flying insects, so there must be lots of those around.
They live in areas up to 2000 mtrs but usually the concentrations are near the coast.

Torture by bird.
Who wouldda thought...

I watched a woman “cleaning” the birds nests after harvesting them, they were in a bowl and it looked like she was sorting through the contents of a vacuum cleaner dust bag. She was picking feathers, dirt, live and dead insects and bits of shit off the nests with her filthy hands then holding them to her mouth to blow the dust off.
The nests themselves were tiny, mostly opaque (apart from the dirt) and looked like plastic.
As I understand it, there is almost no nutritional value to the nests and no medicinal value (its bird spit ffs) they may as well 3D print the things, no one would notice the difference and they’d probably be healthier sans the bird shit taint.

You made the same mistake i made, JB
I always thought it was "bird's nest soup" too.

LOL, but it's actually "bird's nest SOAP", silly us.
I buy it all the time now, that's why i am such a Hamson Man these days
- it contains bee collagen, you know...
http://www.birdnestthai.net/Set+Handmad ... 52123.html

NB punters, Before you go setting up the Vattanac Towers of birds nest houses
- think back to when tulip bulbs were the hottest fashion ticket on the planet.

Market demand fails to energise Cambodia’s bird’s nest market
Reasons cited include the inability to officially export bird’s nests to China and a lack of investment capital from interested parties.
February 18, 2022
PHNOM PENH – Despite high market demand for edible bird’s nests, the prices and investments involving the commodity have not shown significant positive trends in recent years, according to Cambodia Bird’s Nest Federation president Nang Sothy.

Consumed for its perceived health and wellbeing benefits, edible bird’s nests are made from the dried saliva of the white-nest swiftlet (Aerodramus fuciphagus) found throughout Southeast Asia. Traditionally, the processed swiftlet nests are double-boiled with rock sugar to make a delicacy known as “bird’s nest soup”.

Sothy told The Post on February 15 that investments in man-made swiftlet homes had recorded no material positive signs in the last two or three years, even though orders for the commodity have picked up.

He blamed these circumstances on the inability to officially export bird’s nests to China, a general lack of investment capital among interested parties and a legion of operations that merely emulate others without employing the proper techniques, among other reasons.

He said uncleaned edible bird’s nests currently go for $480-$750 per kilogramme and cleaned ones hover in the $1,500-$3,500 range, depending on quality.

Local production is sufficient to meet domestic demand, with copious amounts sent to China via Vietnam, Malaysia and Thailand, he added.

Sothy said there are about 3,000 white-nest swiftlet homes in Cambodia, a figure he noted is overshadowed by Malaysia, Indonesia and Thailand, each of which he said could have as many as 100,000.

Lim Vathanak, owner of the Khmer Natural Bird’s Nest business that manages two such homes in Sre Ambel, Koh Kong province and Veah Rinh, Preah Sihanouk province, said the market has not been so great in the Covid-19 era, with prices and demand dipping to some extent.
https://www.nationthailand.com/international/40012492

UPDATE
Swallows' Nest MOU Signed by Cambodia and China

Cambodian News (Phnom Penh): On 27 October 2022, Cambodia and China signed a MoU on promoting the export of Cambodian swallows' nests to the Chinese market. The signing took place in the presence of HE Chuon Dara, Minister Delegate to the Prime Minister and Secretary of State of the Ministry of Commerce, His Excellency Pan Sosak, Minister of Commerce, Mr. Kao Kosal, Director General of the General Department of Trade Promotion, Ministry of Commerce, and Mr. ZENG Yomin, President of the Cambodian Private Trade Center in Xiamen, China.

HE Chhuon Dara stated that the signing of the MoU is the first step in paving the way for the export of Cambodia's swallow’s nests to China. He commended the leadership of the Ministry and all relevant officials for their efforts to promote the export of agricultural products from Cambodia to China.

Mr. Kao Kosal stated that the MoU focused on main cooperation items including:
1) Finding partners in Cambodia to produce and supply nest products
2) Support for the establishment of a factory in Cambodia to process swallow’s nest products.
3) Promoting the opening of trade channels on swallow’s nest products between Cambodia and China.
4) Strengthening the business network through various business events such as business forums, business matchings, and participation in trade fairs globally