Selfhosted

You would maybe need to configure separate virtual interfaces for each VPN. And do some routing or a local redirecting proxy (tinyproxy is easy) to ensure things go where you want.

On android there are things that allow you to send traffic to different vpns or proxies by setting listening ports. Something like sagernet or proxychainNG or nekobox.

I’m a bit confused on this comment here:

Additionally, I'd prefer not to not do something like: Computer -> Home VPN -> Mullvad server -> destination, as my upload speed is pretty bad and this would throttle every non-local connection

Because you also mention this:

Computer -> Mullvad server -> Home VPN -> Home server

Which would be the same thing, no? You’re just making a connection to the Mullvad server first then your home network?

I’ll share my experience but it looks like it’s not the solution you’re looking for, I opted to use my Asus WRT Router w/ Merlin Firmware to host my VPN server, the Merlin Firmware lets me connect to 5 different VPN clients at a time, in my case 4 different Proton clients and a buddies server, I use the “VPN Director” feature to route my VPN Server through one of the 5 different clients effectively creating the multi-hop.

I personally haven’t noticed much degradation in regard to connection speeds but at the same time I don’t constantly hop VPN clients or have the same internet speeds as you, I typically stick with the server closest to me.

Edit: To help visualize what i mean:

tailscale has Mullvad add-on, but it's a paid add-on, you can self-host tailscale with headscale

"WG Tunnel" on f-droid lets you define a config/native for either mobile or wifi, whichever you want.

two configs on both? It does that. A config on one and nothing on the other? It does that. It swaps whenever your phone moves from mobile to wifi or vice versa.

if neither is selected, it considers it "both".

I have something like this with tail scale. My homeserver has a tail scale docker as well as a docker tail scale. The docker tailscale advertises itself as an exit node. The tailscale docker is gluetunned to an extern wireguard server (your mullvad for example) Now I can connect to my home net with tailscale and toggle the exit node on and off. By adding a different tailscale container with a different wire guard exit you could just toggle the exit node like that.

Seeing as you are using mullvad you could also just pay the monthly sub to tailscale and they connect your tailnet directly to mullvad

I’m pretty sure Tailscale would be a perfect solution here.

You could use the Mullvad given configuration and then also make a peer to your home network, but you're given a specific LAN IP address from Mullvad.

Why don't you just use Shelter to create a work profile on your phone? The work profile can have a second vpn connection. I do this with my homeserver. The apps that connect to the home server are installed in the work profile so they have permanent access to the homeseraer while the normal profile is on my external vpn.