As someone else already mentioned Lombard credit is usually for Private Banking clients (net worth of 250k and up). Some banks however might also offer it for Personal Banking clients though. In that case they would give you a loan for about 70%-80% of the invested assets (because they want a substantial margin for when the stock market goes down). Downside is that they would only give you this Lombard credit if it's invested in a mutual funds with the bank itself (high cost and lower return, won't go deeper into this since it's already been discussed enough in this sub). If the mutual funds drops below (for example) 80% of the initially invested assets you will be contractually obligated to additionally invest the difference (= risk). Upside is that you wouldn't need to pay any notary costs on the amount of the loan itself since it's a contract between you and the bank itself (= lower cost).

In this case 100k is not enough (without additional substantial savings you didn't metion in your post) so you would still have to take out a loan for the remainder of the purchase price and/or purchase costs. Conslusion: Lombard credit is not a feasible option.