I have a tankless with an HE toploader.

A tankless water heater adds a few seconds of time to produce full-hot output, but the physical distance between the heater and the usage point is much more relevant, same as with a traditional tank heater.

The GPM rating of the tankless is not relevant to the washer itself, and is also meaningless in regards to the tankless unless another figure is included, which is the temperature rise the unit can produce at that stated flow rate. Tankless water heaters are sized/rated according to the temperature rise they produce. Cold/unheated water goes into the unit, hot/heated water comes out. The difference between the input temp and output temp is the temperature rise, a measure of how much heat the unit adds to the water flowing through it. For example, consider a unit rated for 60°F rise at 5 GPM. Input water of 65°F flowing at 5 GPM would exit at 125°F. If the input water is colder (45°F) and flowing at the same 5 GPM rate, the output will be only 105°F. Likewise, if the flow rate is slower, the temp rise and output temp will be higher because the water is flowing through slower and is exposed to the heat for a longer time. My HE washer has a flow rate through its internal water valve of about 2.2 GPM. I doubt any HE washer nowadays has valves that allow a 9 GPM flow.

The concern in your situation is the length of the supply line between the heater and washer, which must be purged of standing cold water before hot water arrives at the machine. That standing water, of course, flows right on into the machine when it's turned on. Since HE machines use so little water, that could be an appreciable amount of the total fill. The circulation pump assists by creating an active flow within the hot supply lines of the household plumbing infrastructure, thus effectively reducing/eliminating the standing cold water in the lines. How much it helps the washer depends on where the circulation pump is located in relation to how the household pipe infrastructure branches to the washer. Circulation pumps are often run on a timer for economy. If circulating continuously, the tankless would be activated constantly, and the household plumbing infrastructure would effectively be functioning as a heating radiator. Some pumps can also be activated manually via switches located near usage points (bathrooms, kitchen, laundry). In that case the pump is turned on a couple minutes before hot water is needed to get the line purged. Timer operation is of course more convenient and automatic.

The link below appears to cover your situation. If you can't use one of the proposed solutions, and have to live with "cold water sandwich", you'll want to consider a washing machine that uses its internal heater to guarantee wash temperature for all temperature selections and cycles. I think that's limited to the European brands like Miele, Bosch and Asko.

Here is a link that might be useful: 16. What is a cold water sandwich effect?

Oops, I accidentally clicked the Submit button before finishing the reply.

My washer works fine with my (electric) tankless. I don't have a recirculation pump and my tankless is close to my washer, but I purge the line anyway by setting the washer to diagnostic mode and running the hot water valve (and drain pump at the same time) until the water is flowing hot into the machine. Takes maybe a minute.

Some people have reported trouble with a particular brand of frontloader (sorry, I don't recall which) that pulses the water on/off during fill instead of running it steadily. If hot water isn't running anywhere else in the house at the same time, the (gas) tankless shuts off each time the washer turns off the flow, then has to reignite the burner when the water pulses back on, which causes continual interruptions to the water heating. A recirculation pump may help with that issue, but it would have to run continuously while the washer fills. Another workaround is to run a bathroom or kitchen faucet at the same time to keep the tankless activated. Or even better, avoid that brand of washer.

My LG did that.

We have electric tankless behind the washers wall, so it's only few feet and when using hot water load it's not bad, it takes very short time to heat the water up,only the sanitazing cycle takes a bit to get to the temp.Our LG turns on and off few times and after that it fills it up without interruption. I always use the water plus feature and found out that this helps to get more hot water in.
In the next house we plan smaller tankless unit installed right next to the washer and couple of other units for bathrooms and kitchen.This way there will not be any waste of the hot water traveling through the house.