I ordered something from a small business in the Czech Republic and got a bill in the mail for the tariffs. Item was delivered via fedex, bill came a week later.

I ordered from France several months ago, at a time when their public postal service was confused about tariffs and had announced they would stop delivering to the US. The business assured me my order would get to me regardless (it was a luxury perfumer), and indeed they did - just switched to a private carrier. I did not have to pay any fees on top of the retail price, which was the price listed for every country. It appears they did not pass on the tariffs to me, but perhaps now that has changed.

I am now considering another luxury purchase, this time from Japan, and they note on their website that they do not pass on tariff costs to their US customers.

Yes, on an EU order.

Though it ended up with one of those last-mile delivery services and never arrived.

I have not ordered from Italy. However, I've placed ordere from Spain (EU) and two from the UK.

I did have to pay tariffs on the order from Spain and one from the UK. The other UK order, the shop said they would cover tariffs costs.

The delivery companies were DHL and FedEx. For whatever reason, DHL was considerably cheaper even though the items were similar in value. You should receive an email from from the delivery company stating you must pay the tariff before the delivery date or the item will be returned to sender.

There is a goods supplier I've ordered from every year, but this is the first time since TACO declared tariffs on everything.

Item shipped via Fedex.

Will Fedex hold my package? Deliver and billy me later?

How as the tariff price been compared to your goods purchase price?