I wouldn't say there any major technical hurdles to bootstrapping PoS, the project just has to decide where the initial tokens should go - insiders, ICO, airdrops, etc. Many modern chains have been PoS from the start, like Cardano, Solana, Algorand, Avalanche, NEAR, etc.

Or do you mean in the sense that (some argue) the most fair way to do an initial token distribution is PoW with no premine?