Deposit DOT into parachain child accounts to accelerate opening XCM channels

tl;dr: deposit 2261 DOT into the Polkadot relaychain "Child" accounts of fourteen parachains to make it easier to open XCM channels between chains.

Background:

It takes a bit of work to open XCM channels between Polkadot parachains. Besides XCM runtime configuration, the team needs to deposit DOT into the parachain's Child account, or governance needs to sell some of their token for the DOT. Then Chain A passes a referendum to initiate opening one HRMP channel, Chain B accepts and sends a channel open request back. Then Chain A governance accepts the channel back. 10 dot need to be 'bonded' in each direction, so 20 DOT on each side of a bidirectional XCM channel. If dev teams are primarily working on their own chain's use case they might not spend time figuring out the XCM calls to make this happen. It's also important to know that when you bridge (XCM transfer) your DOT from the relaychain to one of the parachains, the DOT tokens don't actually leave the relaychain but instead are held in the sovereign acct, the "Child" acct on the relaychain corresponding to the destination parachain. Therefore for any DeFi chain receiving DOT, its Child acct will already hold plenty of DOT to use for opening XCM channels. But non-DeFi chains won't naturally have this DOT in their Child accounts.

Problems:

1. Several OG chains STILL only have one or two XCM channels open
2. I hear some users ask when their favorite parachain token will be available on the Hydration DEX and the answer is "once the team opens an XCM channel".

Therefore I'd like to work on submitting lots of parachain governance proposals to open more XCM channels such as:

• Hydra <-> NeuroWeb (OT), EWT, XRT
• Bifrost <-> PEN, ZTG, PLMC, CRU
• Interlay <-> Kilt, ZTG, XRT
• EnergyWeb <-> everyone (but they need to update XCM config?)
• Mythical <-> Bifrost, Interlay, Kilt
• Kilt <-> AssetHub, Interlay, Moonbeam, Astar, CFG, MYTH, PLMC
• CFG <-> Astar, PEN, Composable, INTR, Kilt
• PHA <-> CRU, KILT, MYTH, PLMC

This should make a lot more parachain tokens more accessible to Polkadot DeFi on Hydration, Bifrost, Moonbeam, Astar, increase the amount of XCM traffic, and remove one technical barrier to further integration and use case development between chains.

Solutions:

1. Polkadot Treasury deposit some DOT into the Child accounts of several non-DeFi parachains. (THIS proposal) Then submit gov proposals to each parachain to open channels.
   • Pro: quick and easy
   • Con: risk of parachain teams/governance taking the money. But 100-200 DOT is less than $1k; surely not worth the PR risk
2. Polkadot governance proposals to force open XCM/HRMP channels without requiring a DOT deposit/bond for the channels
   • Pro: no risk of loss of funds
   • Con: removes parachain sovereignty. How do we know if the chain's team and community want to or are ok with opening the channel?
3. Parachain governance proposals to XCM transfer some of their tokens to a DEX, swap for DOT, and then transfer that DOT to the parachain's Child acct on the relaychain. Then submit gov proposals to each parachain to open channels.
   • Pro: no risk of loss of funds
   • Con: more time consuming to craft the 'sell' XCM calls (but doable). One more referenda for each of the chains to pass.
4. Register all assets on AssetHub, and transfer tokens between app chains via AssetHub
   • Pro: don't need more XCM channels
   • Con: I've never seen an example transaction that it works. Creating two separate signed transactions for ParaA -> AssetHub -> ParaB would make the UI worse. Heck, Hydra transfers of vDOT to Interlay still require first sending the vDOT to Bifrost and then to Interlay.
5. Use Hyperbridge ICMP instead of XCM
   • Pro: Parachains register once instead of requiring many point-to-point channels]
   • Con: each parachain needs to integrate several pallets, so adoption will likely be slow.

I collected initial feedback on X and the results indicate that 72% of the 36 voters thought this would be a good initiative to seed several of the child accounts with some DOT (Option 1 above) to accelerate opening channels. A Subsquare discussion post received more feedback and suggestions, but no blockers against pursuing opening more XCM channels using some treasury funds.

https://x.com/spazvt/status/1819234741343678970

Implementation Details:

I propose that we target an account balance of 205 DOT for chains that are more niche or smaller market cap or don't have as many imaginable connected use cases vs a target balance of 305 DOT in the Child accts of 'larger' parachains. In the table below Gap is the amount of DOT that I propose sending to each child account in order to reach the Target balance.

Chain	Parachain ID	DOT in acct	Target	Gap
Centrifuge	2031	141	305	164
Crust	2008	95	205	110
Darwinia	2046	199	255	56
EnergyWebX	3345	0	205	205
Frequency	2091	0	205	205
InvArch	3340	22	205	183
Kilt	2086	25	205	180
Mythical	3369	24	305	281
Neuroweb (OT)	2043	49	205	156
Peaq	3338	25	205	180
Phala	2035	249	305	56
Polimec	3344	67	205	138
Robonomics	3388	0	205	205
Subsocial	2101	63	205	142

This totals 2261 DOT which would be sent from the Polkadot treasury to parachain accounts.

While opening new XCM channels via parachain governance, I'll also register tokens on chains that have the assetRegistry pallet. After I successfully open at least 50 XCM channels, I plan to submit a tip request for around $3000, paid in DOT.