There are several websites that provide lists of compatible Docks for driving 2 or more displays, of course as you have found they require either that the Dock support DisplayLink, or that you connect a USB adapter. A USB DisplayLink adapter should allow you to continue with your current Thunderbolt docks.
The USB C docks will work, I have not found a TB dock that actually has DisplayLink.
Display link also has a list of certified devices on their website. Any of these should work.
I have used the Kensington on my M1 MBP and it took a few short minutes of work, which was complicated since one of the DisplayPort connections was not fully seated despite looking and feeling as though it was. Once I seated that it all worked like a dream.
Some articles that review this include:
https://www.macworld.co.uk/how-to/ho...1-mac-3799794/.
and
https://www.kensington.com/news/dock...le-m1-macbook/
There is also this site that has articles and recommended devices to buy that are all DisplayLink M1 supported: . This has some general comments about the various devices' pluses and minuses.
On another note, I have found that
prices can vary significantly within a short time frame AND MANY ARE currently in short supply (July 2021.)
One thing to be aware of is that many of the docks will say they are Thunderbolt #...compatible, but in fact, they only support the 5 or 10 Gb/S USB protocol. Accurate but also misleading.
So far I have not been able to find a Thunderbolt 3 or 4 dock that has native support for DisplayLink. I contacted Kensington, the maker of my dock, and they said I could connect a USB DisplayLink adapter to a Thunderbolt Dock's USB port with a DisplayLink USB to HDMI or DP adapter, so long as the connection from the adapter to the monitor are the same (e.g. no DP to HDMI adapters.)
I am about to check that out since I have found some issues, as noted in earlier reviews, of slow USB external drive performance that Thunderbolt hopefully resolves.
So far the biggest issues that I have run into have been:
1: Sometimes on reboot have to power cycle the dock to get 2nd external monitor recognized.
2: Unable to cold start from a clamshell mode with BlueTooth keyboard. (Does not recognize keystrokes. This happened before the M1 though as well.)
Other known items, not an issue:
3: The drivers work by "copying" the screen to memory, this causes the Apple Watch to "sometimes" not unlock the computer
4: Since the Driver works by "copying" the HDCP is not present, so protected content will not display. You can always switch to the natively driven screen(s).
Pleasant surprises:
Since I have a 1440 monitor they both drive at 75hz, my monitors' limit.
No noticeable lag between screens and mouse/trackpad input.
That is what I have found so far in the 10-days of testing I have done.